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Not all small turbo engines are more fuel-efficient says Consumer Reports

Consumer Reports isn't letting up on its testing of fuel efficiency claims for various vehicles. According to the publication, small turbocharged engines aren't delivering on the fuel efficiency claims by the manufacturers.

Small displacement turbocharged engines have become common in a variety of vehicles in place of larger displacement, naturally aspirated engines. The claim by the automotive manufacturers is that the small displacement turbocharged engines offer the same power as larger displacement engines and improved fuel efficiency.

Consumer Reports, however, states that in its real world testing many vehicles with turbocharged engines aren't as efficient as the manufacturers claim. The publication recently tested the 1.6-liter EcoBoost in a Ford Fusion and found that the turbocharged version has a slower 0-to-60 mph time than its competitors and achieved only 25 mpg in testing, making it among the worst for fuel efficiency in the recent crop of family sedans.

The publication also claims that the larger 2.0-liter turbocharged four-cylinder, which promises the power of the V-6 with the fuel economy of four-cylinder engine, fails to deliver on either front.


2013 Ford Fusion

Chevrolet is also under fire for the 1.4-liter turbo four-cylinder in the Cruze. Consumer Reports claims that real world performance wasn’t much better than the standard, naturally aspirated 1.8-liter engine and overall fuel economy was similar as well.
 
Ford and General Motors representatives offered similar statements explaining the discrepancy. "When you have an EcoBoost engine, you have the opportunity to have performance and fuel economy, but not at the same time,” said Ford Powertrain Communications Manager Richard Truett. “EcoBoost adds a dimension that you won't get by just making the engine smaller. We're telling the driver, it's up to you on how you want to drive."

"The Cruze turbocharged engine provides a much broader torque curve than a non-turbocharged engine, and that means better acceleration across the rpm range, making for a more fun-to-drive car,” said GM spokesman Tom Read. “However, if you have a heavy foot on a turbocharged engine, you're not necessarily going to see a lot of fuel economy benefits."

The EPA is going to investigate Ford after Consumer Reports and other owners have complained that fuel efficiency doesn't meet the automakers claims in the Fusion Hybrid and C-MAX.

Source: Consumer Reports



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Common Knowledge
By Flunk on 2/5/2013 9:51:46 AM , Rating: 4
I thought it was common knowledge that turbocharged engine efficiency was highly dependant on how you drive them. With these little ones you basically need to drive like a 85 year old grammy to get the rated fuel efficiency.

I suppose it's good to have exposure for the people who don't really follow cars.




RE: Common Knowledge
By Farva on 2/5/2013 9:55:26 AM , Rating: 4
Meh, I have a 2012 Chevy Sonic with the 1.4L Turbo engine and I drive more like a "bat out of hell" than a "granny" and get an average 36 MPG of mostly city (or stop-and-go highway) driving. The Cruze weighs more than my Sonic though so obviously it's performance on both fronts is going to be worse, but a blanket statement by Consumer Reports that these low displacement engines not performing as they are marketed is a bit false.


RE: Common Knowledge
By Farva on 2/5/2013 9:58:19 AM , Rating: 4
Oh, and the Sonic with it's "torquey" engine and a manual transmission is actually a lot of fun to drive too. ;)


RE: Common Knowledge
By tng on 2/5/2013 11:33:22 AM , Rating: 4
quote:
I thought it was common knowledge that turbocharged engine efficiency was highly dependant on how you drive them.
This is true with almost any car, turbos only accent this.

The problem is, that in general, most of the car buying public are not gearheads and what the dealer tells them to sell the car is probably not what they need to hear...


RE: Common Knowledge
By NellyFromMA on 2/5/2013 11:34:05 AM , Rating: 3
How could ANY specific detail regarding turbo-charged applications be referred to as 'common knowledge'?

Common knowledge might be you need to change your oil. The interval MAYBE. How to do it, not so much.

That is the bar for common knowledge in the automtive industry. In other words, safely assume it is NOT common knowledge. The average consumer is nearly always under-informed...


RE: Common Knowledge
By RufusM on 2/5/2013 11:42:21 AM , Rating: 2
As my late uncle would say:

"Any idiot knows that..<insert anything you didn't know about>."

Example: Any idiot knows that vehicle MPG varies depending on how you drive them. Even more with turbo!


RE: Common Knowledge
By Reclaimer77 on 2/5/2013 11:38:07 AM , Rating: 3
No this is NOT "common knowledge" because the average person in this country is a retard. They think car makers can magically deliver insane MPG without having to compromise on anything. Because Obama, or the EPA, or the news lady said so.

Just more evidence of how are committing national suicide by regulating our manufacturing base into extinction. The Government doesn't seem to understand that fuel economy is not the primary factor to the average car buyer. They still have to make cars that people WANT TO BUY so they can make a profit.


RE: Common Knowledge
By Labotomizer on 2/5/2013 1:50:13 PM , Rating: 2
because the average person in this country is a retard.

Amazingly accurate statement there. The reason there is such a huge need to stretch MPG in the first place is because of the ridiculous CAFE regulations. I understand wanting companies to offer more fuel efficient models, although that should be chosen by consumer demand and not government regulations, but to say "Your average across your fleet must be XX" is insane. Some people NEED high powered vehicles. Some people just WANT them and are okay with paying for it at the pump. My friend who just bought the 2013 GT 500 knows full well he's going to pay for more gas. But he can easily afford it, so he should have that option. The way things are going we won't much longer. It's sad.

Of course, who cares if we ruin the auto industry. The government is here to fund them and make sure everything is okay.


RE: Common Knowledge
By Jeffk464 on 2/6/2013 10:31:46 AM , Rating: 2
MPG has had an impact on car buying. People are choosing 4cyl sedans over the v6 engines in much larger number and crossovers are pretty much replacing mid sized truck based SUV's.


RE: Common Knowledge
By Reclaimer77 on 2/6/2013 11:04:04 AM , Rating: 1
I never said it wasn't a factor. I just said it wasn't a "primary" concern. If it was, hybrids would be accounting for WAY more than the ~6% of sales they do now.

One could just as easily say the trends you've brought up have more to do with the economy sucking balls for the past 5 years, and massive consumer uncertainty, than fuel economy as well.


RE: Common Knowledge
By Jeffk464 on 2/6/2013 9:21:41 PM , Rating: 2
Gas prices, gas prices, gas prices. :)
I bought my v6 tacoma prerunner back when gas was around $2.50, given current trends I would never buy a vehicle with that kind of mileage now. And my Tacoma could be worse 18-19 in the city and 25ish on the interstate with cruise on.


RE: Common Knowledge
By dgingerich on 2/5/2013 11:46:25 AM , Rating: 2
This is specifically why I got my V6 (2005 Monte Carlo) instead of a turbo I4 when I got my last car. I find a V6 is much more predictable, offers better off the line power, and overall better gas mileage for the way I drive. I get 25-26mpg out of my car, even after 7 and a half years. If I really put my foot down, I get as low as 20. However, a turbo I4 would be worse on both cases, and offer lower off the line power, which is where everything counts. It's that 0-40 time that makes all the difference in day to day driving.


RE: Common Knowledge
By degobah77 on 2/6/2013 10:15:13 AM , Rating: 1
My turbo'd 4-cyl (~270hp) gets the exact same gas mileage if not better if I really lay off the boost, and will more than likely wreck you off the line.

The trick is to not buy a crappy car and then wonder why it sucks.


RE: Common Knowledge
By Jeffk464 on 2/6/2013 10:32:21 AM , Rating: 2
bmw 3?


RE: Common Knowledge
By degobah77 on 2/6/2013 11:23:33 AM , Rating: 2
I don't drive status symbols.

Subaru got my money.


RE: Common Knowledge
By Jeffk464 on 2/6/2013 9:25:40 PM , Rating: 2
Subaru's are good cars. I thought about getting the new outback wagon for a while, in forest green of course. Toyota put some major updates on subaru's boxer engine for the new sports car, it would be nice if that went across the entire product line.


RE: Common Knowledge
By Jeffk464 on 2/6/2013 10:28:33 AM , Rating: 2
How you drive greatly effects your mileage in any car. I'm always amazed at the guys driving the raised full sized trucks that always have to floor it to get to the next stop light or pack of traffic. They must be getting under 10mpg.


Doesn't EPA determine the mileage?
By Milliamp on 2/5/2013 9:49:19 AM , Rating: 2
I thought the official MPG displayed on the sticker is determined by EPA (Environmental Protection Agency) testing.

But yeah nobody ever believed turbo charged engines would deliver the power of a v6 with the fuel economy of an i4. AFAIK Ecoboost works by bypassing the turbo when in eco mode so it is generally just a naturally aspirated i4 doing the work until you step on it, right?

It is kind of the same principal as larger engines use when they deactivate some of the cylinders that are not in use. My v6 uses 4 cylinders in "eco" mode but if I drive with a lead foot it doesn't stay that way for long.




RE: Doesn't EPA determine the mileage?
By Manch on 2/5/2013 10:46:35 AM , Rating: 3
All turbo/forced induction pretty much work the same. They engage based off of the throttle. For a turbo, you step on gas, the exhaust compresses, spins the turbo, turbo compresses the air, shoves it into the intake manifold, add a little more gas a timing and you get more power. With a PD same things except since it's powered by the crank like all of your accessories. it takes a little bit of power from the engine to compress the air, but you get more power in return.

The end result is the same more air, more fuel, more power, lower mpg.

I have a supercharger on my 06 mustang, and when I drive normal, as in stay out of boost, I see decent mpg 25mpg avg (cars also highly modified). If I step on it though, yeah my mpg goes to hell.

cylinder deactivation primarily for cruising at a constant speed and is different from above. You're cutting spark/fuel leaving the exhaust valve open(some cars do this differently) to those cylinders so they are just along for the ride. The remaining active cylinders have enough power to overcome the drag of the dead ones because at typical cruising speeds on the highway you're only using about a third of the power produced by each cylinder. so during cruising, you see a bit of an mpg bump. Once you start modulating that peddle though, those cylinders will come back on.

So you can see "V6" power out of a four banger at WOT, but you definitely will not see the I4 mpg at the same time.

If you want to get into the weeds on the difference google supercharger vs turbo, they have some good articles that explain it out in better detail. Also check out variable displacement & cylinder deactivation.

Sorry if this post is a bit lengthy, I'm trying not to go crazy while Im on hold. Been the 10th person in line for what seems like forever!


RE: Doesn't EPA determine the mileage?
By Milliamp on 2/5/2013 1:10:33 PM , Rating: 2
I'm sort of familiar with Turbo chargers and super chargers but for some reason I was thinking EcoBoost was a larger improvement on the standard turbo design rather than just a marketing name.

Basicially with a turbo the fan is always inline in the exhaust system and connected to the turbine, but at low speed it doesn't provide much boost.

With the EcoBoost I was thinking they disengaged the inline turbo fan from the turbine reducing back pressure and allowing the engine to run naturally aspirated while not under boost.


By Spuke on 2/5/2013 3:59:09 PM , Rating: 2
EcoBoost is just a marketing name. Since turbo's are exhaust driven, how do you remove it from the exhaust stream? And with a large enough exhaust there won't be a back pressure issue. Besides it's exhaust gas flow you're more concerned with not back pressure. BTW, when you're not in boost you ARE running normally aspirated.


By tastyratz on 2/6/2013 10:45:56 AM , Rating: 2
it really doesn't make much of a difference there because there is an equalization ratio. Don't forget for every xcfm of exhaust flow pushing against one side, there is also another xcfm of flow pulling against the intake side. With air traveling both ways you end up almost with a free lunch of sorts making it take minescule amounts of power to be in stream and not pressurized.

What most people don't realize is a turbocharger can see 100krpm, and piping is generally designed around avoiding airspeeds that break the sound barrier under boost. That is when these losses multiply and mileage plummets (for a whole host of other reasons too, just keeping this short)


RE: Doesn't EPA determine the mileage?
By Jeffk464 on 2/6/2013 10:36:01 AM , Rating: 2
Cylinder deactivation sounds great in concept but most cars I have seen haven't shown much MPG increase, seems like about 1 mpg. Seems like a cheaper lower maintenance alternative to turbo 4's though.


By Jeffk464 on 2/6/2013 10:37:17 AM , Rating: 2
I still think a really solid 4cyl with 6spd transmission is a pretty good choice for a mid sized family mover.


By NellyFromMA on 2/5/2013 11:35:16 AM , Rating: 2
Basically, the track used to determine mileage is skewed in favor of this application anyways. Now THAT is common knowledge. Eh, maybe not...


RE: Doesn't EPA determine the mileage?
By theapparition on 2/5/2013 12:58:45 PM , Rating: 3
quote:
I thought the official MPG displayed on the sticker is determined by EPA (Environmental Protection Agency) testing.

No, the EPA doesn't actually do any testing except for rare instances. What they do is come up with the procedure for testing, that all manufacturers are supposed to follow. The automaker then test the car to the EPA procedure and then submits the results to the EPA.

quote:
AFAIK Ecoboost works by bypassing the turbo when in eco mode so it is generally just a naturally aspirated i4 doing the work until you step on it, right?

That's how EVERY forced induction application works. There is a blow-off valve that is connected to vacuum. During normal driving, the valve is open allowing the turbo or supercharger boost to disipate to ambient. But when the vacuum increases (ie, you step on it), the valve closes and the pressure increases in the intake.

Now how you tune the system and adjust the blowoff valve determines whether you are trying to make the most power or be more efficient. There's no magic to the Eco-boost system other than marketing with a cool buzz word.


RE: Doesn't EPA determine the mileage?
By Spuke on 2/5/2013 4:00:39 PM , Rating: 2
quote:
There's no magic to the Eco-boost system other than marketing with a cool buzz word.
X2, seems as if they have some people fooled though.


By theapparition on 2/5/2013 6:03:46 PM , Rating: 2
People do love themselves some good marketing, don't they. They eat that crap right up.

If I have to hear about a "Retina" display one more time.....


RE: Doesn't EPA determine the mileage?
By roykahn on 2/5/2013 9:43:27 PM , Rating: 3
quote:
No, the EPA doesn't actually do any testing except for rare instances. What they do is come up with the procedure for testing, that all manufacturers are supposed to follow. The automaker then test the car to the EPA procedure and then submits the results to the EPA.


I think I've found the problem :) What's the point of having the manufacturers claim fuel usage figures? As if they're not going to lie to make their cars appear more fuel efficient. That's almost as bad as believing the "official" US statistics of civilian casualties from its war on terror.


RE: Doesn't EPA determine the mileage?
By theapparition on 2/7/2013 11:55:13 AM , Rating: 2
quote:
What's the point of having the manufacturers claim fuel usage figures? As if they're not going to lie to make their cars appear more fuel efficient.

Several fold.

First off, the government can't do anything efficiently and timely. Do you honestly want them testing every car? That's our tax money at work, and to be honest, it would be wasted.

Secondly, you claim that if someone is in control of the results, they'll intentionally file false ones. That logic is flawed. By the same metric, everyone who files their taxes lies to get a better refund.

What you do is establish a list of rules, and punishments for breaking those rules. That's how the law works. No, I'm not being an idealist, but this is how society works.

And if you worked in the industry, you'd find that this is the norm. When creating a new jet, the Air Force doesn't test, they monitor the test being done by the builder (eg, Lockheed). The Air Force comes up with the requirements, and it's up for the manufacturer to meet those requirements. So they are tested, and the results submitted or demonstrated. Meeting those goals are also a requirement for payment. A super gross over simplification, but you get the idea.


RE: Doesn't EPA determine the mileage?
By roykahn on 2/8/2013 8:01:01 PM , Rating: 2
quote:
but this is how society *should* work.


I fixed that for you. When there's an economic incentive to cheat, then people will cheat. THAT is reality.


By theapparition on 2/11/2013 10:53:58 AM , Rating: 2
Unless there are suitable punishments in place to deter such cheating.

Hyundai found out the hard way recently. Ford may be next.


RE: Doesn't EPA determine the mileage?
By Jeffk464 on 2/6/2013 9:30:12 PM , Rating: 2
You sure it still works this way? Seams like it would all be done with sensors and actuators these days. I know the modern applications can reduce the turbo PSI when knocking is picked up by the computer.


By theapparition on 2/7/2013 11:42:16 AM , Rating: 2
There may be advancements, but the basic system still works like this.

As for reducing boost in knock applications, that's incredibly dumb. MUCH easier for the computer to retard timing in a separate table. That can be done in milliseconds vs seconds for boost to be dissipated. Much safer this way.

Now, the way you heard it was probably that the power was reduced when knock was detected and someone assumed that boost was decreased. That's much more likely.


By tayb on 2/5/2013 11:45:00 AM , Rating: 1
Were the blowhards at CR actually testing 0-60 speeds at the same time they were testing fuel efficiency...?

Consumer misInformation.

"I have a conclusion. I will now devise a test to prove this conclusion."
-Consumer Reports




By Voldenuit on 2/5/2013 2:17:04 PM , Rating: 3
quote:
Were the blowhards at CR actually testing 0-60 speeds at the same time they were testing fuel efficiency...?


No. From Consumer Reports' page on their testing procedures:

quote:
We perform our own fuel-economy tests, independent of the government's often-quoted EPA figures and the manufacturers' claims. Using a precise fuel-flow measuring device spliced into the fuel line, we run three separate circuits. One is on a public highway at a steady 65 mph. That circuit is run in both directions to counteract any wind effect. A second is a stop-and-go simulated city-driving test done at our track. The third is a 150-mile "one-day trip" using several drivers taking turns around a 30-mile loop of public roads that include a highway section, secondary roads, and rural byways. CR's overall fuel-economy numbers are derived from those three fuel consumption tests.


http://www.consumerreports.org/cro/2012/12/how-con...

Seems more likely blowhards on the internet are jumping to conclusions without bothering to research their assumptions.


By Spuke on 2/5/2013 4:02:31 PM , Rating: 1
quote:
Seems more likely blowhards on the internet are jumping to conclusions without bothering to research their assumptions.
Soooo how does one directly compare the results of one test to the results of another exactly?


By Voldenuit on 2/5/2013 6:18:34 PM , Rating: 3
quote:
Soooo how does one directly compare the results of one test to the results of another exactly?


Are you referring to comparing CR's results for different cars or comparing CR's results to EPA mpg figures?

For the former, CR's results should be relatively consistent as they test the same procedures and use more than one driver to generate each data point. So it should be valid to compare different cars using just CR's mpg figures.

Comparing CR's results with the EPA's is a little trickier, as the testing methodologies are different. However, it's worth noting that while there are many vehicles whose CR-attained mpg results match or exceed the EPA figures, every single turbo Ford in the test failed to meet its EPA rating on the CR cycle.

With a lack of information on what the exact cause is, I can only speculate that one or more of the following postulates are to blame:

1. CR's tests are worthless. I find this explanation the least likely as they should at least be useful for evaluating different vehicles being tested to CR's standard.

2. The EPA test procedure is flawed. There have been allegations that the EPA cycle does not replicate real world use and that manufacturers are gaming the system to achieve inflated numbers.

3. Ford is fudging their mpg figures. Whether this is from honest mistakes or a deliberate attempt to mislead the public is open to conjecture.

Personally, I consider a combination of 2. and 3. to be the most likely, but that is simply opinion for now. For the record, I average better than quoted mpg (by about 15-20%) in my wife's Fiesta (1.6L NA) and spot-on mpg in my Lancer Ralliart (2.0T). We were getting worse than quoted mpg (by about 10-20%) in our old 2008 G35x, so "YMMV" really does apply in all cases, it seems.


By Spuke on 2/5/2013 7:09:22 PM , Rating: 2
quote:
so "YMMV" really does apply in all cases, it seems
It does seem that way and thanks for the reply. Anecdotal but I have found Nissan's to be less fuel efficient than advertised in my driving also. My present car is spot on although I wonder how you have to drive and in what conditions to get their city rating (19 mpg). My worst is 23 and that was after a week of city only, spirited driving.


By Rukkian on 2/6/2013 11:11:05 AM , Rating: 2
Unless the epa tests fords cars and concludes they lied, at this point, I am thinking number 2 is correct. There are numerous cars that are made to specifically ace the test. The fact that several plug in hybrids shut off their electric motors at 62mph (2 above what the epa test goes to from what I understand) points to gaming the system.

We will see now that the epa is investigating, and Ford will be hit with big fines and, more importantly, very bad press if they are found to be lying. If the epa comes up with basically the same numbers, then I think the test maybe needs to be updated, but that would probably take 10 years due to the way Washington works.


Weight
By Brandon Hill (blog) on 2/5/2013 10:19:43 AM , Rating: 2
I think a big problem with the Fusion is weight. In 1.6t guise with an automatic transmission (the volume model), the Fusion weighs 3420. That's a lot of weight for a 1.6-liter engine, even with a turbo.

You have to drive it like a little old grandma to get anywhere close to EPA numbers. Drive it like a normal human and get a little into boost (not even hot dogging it) and your mileage drops like a rock.

With competitors using 2.4-liter and 2.5-liter engines, you don't need to be nearly as cautious when driving to get good fuel economy.




RE: Weight
By Spuke on 2/5/2013 2:06:52 PM , Rating: 2
Same with a boosted 2.0L IMO. I don't drive like a grandma and get consistent 27-28 mpg which is right at EPA hwy for my car, Pontiac Solstice GXP. IF I do drive like granny then I get 33 mpg. Worst fuel economy was 23. I know a guy with my same car that wonders how I, or anyone with our car, gets over 20 mpg (he gets 19 consistently). When I got the 23, I thought I was hammering on it too. I wonder how you have to drive to get it under 20 consistently.


RE: Weight
By DT_Reader on 2/5/2013 7:10:17 PM , Rating: 2
You're absolutely right. Fuel consumption has more to do with vehicle weight than anything else. A turbo 4 must weight less than the equivalent 6 for any fuel savings. And you have to keep your foot out of it :-)


RE: Weight
By JediJeb on 2/5/2013 8:53:17 PM , Rating: 2
Vehicle weight and the torque output and torque curve are more important than pure HP numbers. If an engine gets more torque at a low rpm near what you are cruising at than another then that engine can be geared to produce better mileage.

I had an old 2.3L I4 Mustang that got worse mileage than most 5.0L V8 models. The little engine just did not have the power and had to be geared much lower just to move the car. Another way to think about it is displacement versus operating rpm. A 1.6L engine operating at 5000rpm displaces the same volume of air/fuel as a 2.67L engine operating at 3000 rpm. Given that stoichiometrically you get the same amount of energy from the same amount of fuel/air(minus the minor efficiency differences) then you should get the same mileage from a 1.6L engine running 5000rpm to achieve 70mph as you would from a 2.67L engine running at 3000 rpm to achieve 70mpg. Both of those engines are consuming 4000L of fuel/air mixture per minute running at the respective 5000 and 3000 rpm and 4000L will have the same BTUs produced in each engine.

Now where you can make one engine better than the other is in the design of the leverage in the piston/crankshaft geometry to gain more torque at lower rpm so that your gearing can be higher(lower ratio)at the final drive axle. If you can't manage to get the torque needed at a low enough rpm on the little turbo I4 it will not beat the mileage of a larger engine that can.

This is why I like the 4.9L I6 in my truck over the 5.0L V8 because the I6 has much more torque at lower rpm. While I can not rev the engine up over 5K rpm and smoke the tires, I can be in 5th gear by the time I am at 30mph without bogging the engine down. Long stroke inlines for low end torque, short stroke engines for higher rpm horsepower. Both have their uses and their detriments.


Isn't this what I've been saying?
By EricMartello on 2/5/2013 1:01:05 PM , Rating: 1
Turbos do not boost engine efficiency; they boost effective displacement which allows for a higher specific output (the old HP per liter metric that ricers often point at as an indication of how superior their vtec is).

When you add a turbo or SC to a car you are increasing the amount of air entering the cylinders. In order to produce more power you also need to increase the amount of fuel entering the cylinder. The air:fuel ratio has to stay the same to keep the engine running optimally or you'd get a lean condition that would eventually cause the engine to overheat.

I really like turbo engines and sports cars with them are a lot of fun to drive but they are not going to beat out econo boxes as fuel sippers. The idea that you can replace a V6 with a turbo I4 and see improved fuel economy under normal driving conditions (i.e. stop and go traffic) is laughable. Meanwhile the V6 is going to be quite a bit smoother in most cases even if the turbo 4 has more torque and power.




RE: Isn't this what I've been saying?
By PaFromFL on 2/6/2013 8:02:09 AM , Rating: 2
Turbos allow smaller engines that are more efficient because they have less internal friction, and the reduced weight improves overall vehicle efficiency. Turbos also produce more lower end torque so the average engine rpm is lowered, also increasing efficiency. However, the trend is toward regenerative braking which reduces some losses associated with higher curb weight, and better materials, drivetrains, and lubricants have reduced the impact of friction.


RE: Isn't this what I've been saying?
By Manch on 2/6/2013 10:08:26 AM , Rating: 2
What does regenerative braking have to do with turbos?

Sure, turbos do allow the engine to produce more lower end torque but only when under boost. When they're under boost though they aren't any more efficient than an NA car sucking down gas. More often that not they're worse. It doesn't give you an lower average rpm either. Also a lower avg rpm doesn't always mean more efficient, nor is avg rpm an indicator of anything by itself..


By PaFromFL on 2/6/2013 3:48:10 PM , Rating: 2
The trend toward regenerative braking and less friction is reducing the relative advantages of smaller engines.

High rpm operation loses significant amounts of power to frictional losses and fluid turbulence. To test this, put your car in a lower gear and watch your mpg drop like a rock. A high revving normally aspirated engine can produce the power of a similar sized low revving turbocharged engine, but at much reduced efficiency. Manufacturers have gone to a whole lot of trouble (warranty nightmares) to use turbochargers because of CAFE standards.


By EricMartello on 2/7/2013 9:51:50 AM , Rating: 1
quote:
Turbos allow smaller engines that are more efficient because they have less internal friction, and the reduced weight improves overall vehicle efficiency.


No, they do not have less internal friction. They do have lower static compression, but for a given power output both a turbo and NA engine will consume similar amounts of fuel which is what we're talking about. Efficiency is a measure of fuel consumed per unit of power produced.

Turbo engines are not substantially lighter than their NA counterparts because turbo engines (the reliable ones) have iron blocks. An NA engine can be perfectly reliable with a substantially lighter aluminum block.

quote:
Turbos also produce more lower end torque so the average engine rpm is lowered, also increasing efficiency.


That depends how the engine is tuned and what type of turbo you are using. A small turbo will produce more low-end torque at the expense of mid-range and top-end power - this translates to anemic performance on the highway when trying to pass or merge.

There is a myth being perpetuated on many car forums that engines that produce large amounts of low end torque are "better" because "most driving occurs at this RPM". This is not true. Your engine will regularly spin up past 3-4K RPM during normal driving unless you're driving like granny, and your low-end torque will nose-dive right around 4K RPM which means the acceleration from ~30 MPH to ~75 MPH (typical highway speeds) is going to be pitiful.

The IDEAL is an engine that has a broad, flat torque curve that does not fall off and allows the engine to rev higher and produce more usable power.

quote:
However, the trend is toward regenerative braking which reduces some losses associated with higher curb weight, and better materials, drivetrains, and lubricants have reduced the impact of friction.


Regenerative braking is not relevant in this discussion. That has to do with using braking forces to charge a battery of a hybrid or electric vehicle rather than dissipating all of that energy as heat. It adds cost and complexity to the vehicle, with an unclear advantage in terms of improving efficiency.

quote:
High rpm operation loses significant amounts of power to frictional losses and fluid turbulence.


That's simply false.

quote:
Turbos also produce more lower end torque so the average engine rpm is lowered, also increasing efficiency.


Also false. You don't seem to get it. Torque is the ability of an engine to move a given weight a certain distance. Power determines how quickly the torque can be applied. It has nothing to do with a turbo - it's how the engine is configured.

There is no "efficiency" gain from a low-end torque bias in a vehicle that is not REGULARLY towing, plowing or otherwise moving large loads at slow speeds. This is marketing mythology that is highly prevalent on VW and Audi forums as justifications for how "great" the 2.Slow T engine is that seems to be in all of their cars.

quote:
However, the trend is toward regenerative braking


There is no trend toward regenerative braking and you clearly don't understand what it is or how it works...so why bother bringing it up?

Go inflate your tires with helium so that your "effective weight" is reduced and your car drives like "it's floating on a cloud". $200 per tire filled.


Consumer Reports is at it again...
By RandomUsername3245 on 2/5/13, Rating: 0
RE: Consumer Reports is at it again...
By Nutzo on 2/5/2013 12:56:28 PM , Rating: 2
Yet they get close to the rated milage on many cars such as the Camry and Prius.

Thier complaint is with a few of the newer card that are getting much worse than the rated milage.


RE: Consumer Reports is at it again...
By Spuke on 2/5/13, Rating: 0
By theapparition on 2/5/2013 6:11:44 PM , Rating: 1
Basically.........NO!

But while CR is clearly biased, and tends to rate things like the amount of force used to close a door or number of cup holders higher than more important things, I do think they have some validity with these tests.


RE: Consumer Reports is at it again...
By DT_Reader on 2/5/13, Rating: 0
By Dorkyman on 2/7/2013 4:17:16 PM , Rating: 2
I don't see that.

CR employs a bunch of engineers who look at things from a logical perspective. They usually lay out their criteria in advance so the reader can judge for oneself whether those attributes valued by CR are relevant. As an EE myself I find the tests and conclusions very informative.


I thought the C-MAX would be a Prius Killer?
By rkramer40 on 2/5/2013 10:59:18 AM , Rating: 2
I thought the C-MAX would be a Prius Killer? As a cross over buyer I feel deceived. I want to support US companies and US jobs. What was Ford thinking when they published 47/ 47 estimates? I would have been ok with low 40's but low 28-33 is not even in the ballpark. Mark my words there will be no fix for this. Ford should offer to take the cars back or offer cash compensation to offset the mileage claims. The EPA estimates will have to be adjusted to the mid 30's and sell the cars as is. My dealer’s sales and service department were ok at the beginning of the complaint process, but now have turned hostile and un-professional.

Ronald Kramer
Yankee Ford Customer
South Portland, Maine




By Nutzo on 2/5/2013 1:00:32 PM , Rating: 3
Ford even left the spare tire out of the C-Max to save weight, yet can't get the same milage as the heaver Camry Hybrid.

It appears that Ford optimized the C-Max to the EPA testing, and it didn't translate well into the real world. It's going to hurt them in the long run, as people will not trust them.


Weight is important!
By aspartame on 2/5/2013 10:02:34 AM , Rating: 2
The weight of the car is the most important factor in fuel economy. It is natural to expect a 1600 kg car to consume about twice as much as an 800 kg car despite having the same engine size. Another issue is Ford diesel engines are produced by Peugeot, which are technologically inferior to the competitors.




Is it just me...
By Erudite on 2/5/2013 10:02:42 AM , Rating: 2
Or is this mostly common sense? The main reason, as far as I know, for using turbo chargers on smaller engines, was so you could have the higher performance if you needed it, along with the better gas mileage, when you didn't need the better performance. I have yet to talk to anybody with an EcoBoost (including the one in the Fusion) that hasn't liked them. Sure, they might not get the gas mileage that a non-turbo engine gets, but they are a lot more fun to drive - at the cost of fuel economy.

You can drive your little non-turbo 4 banger like it is a dragster and get mediocre gas mileage, too. But it won't compare to the drive a turbo charged engine will give you.

I think the bottom line is that these types of engines are marketed to the person that wants more power but doesn't want a vehicle that gets 10 miles to the gallon. Or doesn't want to put diesel in the tank at $4.00+ per gallon, though that might net you better fuel economy in the long run.

I had a 97 Ford Explorer with a 5.0 V8 that I could get almost 20 MPG with, and a 2007 F150 that wouldn't get more than 15 MPG no matter how I drove it. Now I have an 09 Escape with a 3.0L V6 that I can get almost 30 MPG on the highway if I'm careful how I drive. Or I can drive it like crazy and get 20 MPG. But it is pretty light weight if you compare it to some of the vehicles that they put smaller engines with turbos in. (Read: Ford F150, 6' Bed SuperCrew @ 5,731 lbs curb weight)

Just my 2 cents.

Curb weight source: http://media.ford.com/images/10031/2012_F150_Specs...




By Samus on 2/5/2013 10:27:29 AM , Rating: 2
Hey Consumer Reports, why don't you learn how to drive a turbo before you judge them? You can't drive them the same way you drive a naturally aspirated engine and expect the same fuel economy. Not only is it bad for emissions (older turbo engines often failed emissions tests because the testing center driver lacked knowledge of how to dyno them properly) but without boost, they simply wont run efficiently.

That is to say, when accelerating, you must be at >50% throttle, and when coasting, you must be between 1800-2200RPM in a 4 cyl, 1600-2000RPM in a 6 cyl, and 1200-1500RPM in a 8 cyl. Anything under will bog it down, anything over will cause it to be 'boosting' when coasting, which needlessly produces power that will be released by the blow-off.

If you can't achieve these figured with the automatic they are equipped with, then you need to have the manufactures reprogram the automatics (most turbo's with automatics I've driven adhere to these figures) or get a manual.




Turbo with a stick
By Fujikoma on 2/5/2013 11:09:12 AM , Rating: 2
My 1980 931 could get 30 mpg without turbo and 20 mpg with the turbo. I just had to make sure I didn't push the rpm past 3200. I rarely used the turbo for normal driving. Using an automatic would probably require most people to pay attention to the sound of the engine for feedback on their driving, which I don't think that they're willing to do.




Displacement
By km9v on 2/5/2013 11:18:17 AM , Rating: 2
Mfg.s also try to keep engine displacement low for markets in places like europe that base auto taxes on the engine displacement. I think most EU countries have lower taxes on cars w/ less than 2 L engines. As far as efficiency is concerned, MPG is totally dependent in driving style.




By ssnova703 on 2/5/2013 11:57:01 AM , Rating: 2
Turbo's can be done right, with the power of a bigger motor while achieving better mileage than a bigger motor. Look at the hefty/porky VW GTi's out there, or the twin-scroll turbo Hyundai Sonata(despite their recent EPA fiasco, it's still decent). Good pull/power with respectable mileage when comparing them to respective N/A motors (and considering mileage too).

The cars in question were just not done right, like others mentioned too heavy, perhaps unrefined tuning on the motors, etc. I haven't driven them so I will admit I can't say, but the numbers speak when compared to other cars out there who did it "right".




SOS, DD
By Beenthere on 2/5/2013 1:21:52 PM , Rating: 2
Most people fail to understand that their driving style can alter the mpg by 30% or more. The car maker certified mpg rating is from a standardised chassis dyno test that sorta represents what the EPA believes is a normal consumer driving style. Naturally with people paying a lot of attention to these mpg ratings, the engineers tune the cars to get the best mpg in the standardised test, as is normal and reasonable. The problem is that most people don't drive exactly like the standardised mpg test and as a result they don't get the same mpg.

This isn't rocket science or deception, it's just a different driving style from the standardised mpg test - which an educated person should already know after 20+ years of EPA mandated mpg labeling.

FWIW, I've never had any difficulty meeting the advertised mpg in numerous vehicles but I know how to drive conservatively. I also know that in city traffic you'll rarely ever come close to the advertised city mpg in most cars due to the length of time of the traffic lights, how many stop signs there are, how slow the traffic is moving, how much rubber-necking there is, etc.




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