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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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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.


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