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2008 Toyota Highlander Hybrid - images courtesy Toyota Motor Company
Toyota revamps its Highlander Hybrid, carries over the powertrain

Toyota continues its push for hybrid vehicles with the new 2008 Highlander Hybrid. The new Highlander Hybrid and is based on the new Toyota Camry/Avalon chassis and rides on a wheelbase that is 3" longer. The vehicle is also 3" wider and 4" longer than the previous Highlander Hybrid.

Sadly, the powertrain for the 2008 Highlander Hybrid is a carryover from the previous model. In this case, the old 3.3 liter V6 (which itself is an outgrowth of the even older 3.0 liter corporate V6) and continuously variable transmission (CVT) is still being used to carry the majority of the load on the vehicle. There was speculation that the new 3.5 liter V6 would also be paired with the Synergy hybrid system used on the 2008 Highlander hybrid, but keeping the price down on the model was probably the reasoning for the carryover.

That being said, the Highlander retains its EPA rating of 31MPG/27MPG city/highway despite picking up an additional 500 pounds of heft. The 2008 Highlander Hybrid also offers the option to shut off the gasoline engine completely and run solely on battery power according to AutoblogGreen. The only problem is that the Highlander Hybrid’s NiMH batteries mean that you’ll only be able to travel an astonishing one mile on battery power alone.

GM’s 2009 Saturn Vue Green Line promises to deliver as much as 10 miles of battery-only power thanks to its lithium-ion batteries.

Pricing has not yet been announced for the new 2008 Highlander Hybrid, but expect modest price increases over the 2007 model. The 2007 model retails between $32,490 for a FWD Highlander Hybrid Base to $36,550 for an AWD Highlander Hybrid Limited.



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RE: ignorance
By ElFenix on 2/7/2007 8:28:43 PM , Rating: 2
the layout of the engine has very little to do with fuel consumption. V8s don't necessarily guzzle gas, and V6s don't necessarily improve consumption. usually a V8 is tuned for more performance and in a heavier car than a V6. those factors are more important than the layout of the engine.


RE: ignorance
By DocDraken on 2/8/2007 10:54:59 AM , Rating: 2
quote:
the layout of the engine has very little to do with fuel consumption.


Actually the most important aspect of fuel consumption is internal friction in the engine. A V8 has more internal friction than a 4 cylinder.

So for example if you have a 300 HP 4 cylinder turbo engine and a 300 HP naturally aspirated V8, the V8 will have poorer total fuel mileage, even though it's got the same amount of power.

The car mentioned in the article above is rediculous, since you can get a turbocharged 4-cylinder stationcar that's pretty much just as fast and has similar space and just as low fuel consumption without having expensive and heavy batteries. Unfortunately people think they need a big V6 or V8 even though you can get the same power with a 4 cylinder and have better mileage too.


RE: ignorance
By masher2 (blog) on 2/8/2007 1:21:49 PM , Rating: 1
> "Actually the most important aspect of fuel consumption is internal friction in the engine..."

No, the most important factor by far is simple Carnot losses inherent in any heat engine. In second place is rolling resistance, including frictional losses from wheel to road, and those from air resistance.

Internal friction within the engine is quite low...which one can see from noticing that an engine at idle uses nearly no gasoline, yet is able to overcome that internal friction to keep moving.

> "The car mentioned in the article above is rediculous, since you can get a turbocharged 4-cylinder stationcar that's pretty much just as fast..."

You forgot a little thing called torque. A turbocharged 4-cylinder may have equal horsepower, but its still going to have far less torque.



RE: ignorance
By miekedmr on 2/8/2007 3:22:30 PM , Rating: 2
Not arguing really, I just want to clarify, because people don't seem to understand the relationship between horsepower and torque.

Horsepower = torque * RPM

A V8 would tend to have lots of torque at a low rpm, giving it a high PEAK torque rating relative to its PEAK horsepower. A turbo 4 cylinder that makes all its torque at a high rpm would have a high peak horsepower relative to its peak torque, because HP is a function of rpm too.

Here's the misconception: a turbo 4 cylinder might make the same 250ft-lb of peak torque at 6000rpm as a v8 at 3000rpm, but because of the peaky no-low-end torque curve, it gets labelled as having "no torque", when it really has plenty. It's just at a high rpm. Torque is not a measurement of output at low rpm...


RE: ignorance
By masher2 (blog) on 2/8/2007 4:02:31 PM , Rating: 1
> "a turbo 4 cylinder might make the same 250ft-lb of peak torque at 6000rpm as a v8 at 3000rpm..."

If that 4 cylinder had the same torque at 6000rpm as a V8 did at 3000rpm, it'd be outputting twice the horsepower though. That's pretty rare...and its not the situation we're discussing.

The OP mentioned a 4-cyl engine matching a V8 in peak power output, and then (incorrectly) assuming that the engines had equivalent performance. In this case, the smaller engine compensates for its lesser torque by a higher rpm peak on its peak power curve. So though the horsepower is equal, the torque is less. And-- most importantly for people who buy trucks and SUVs-- the low-end of the torque curve is far less. If that wasn't true, people would be towing powerboats and mobile homes with turbocharged Civics.

So while a turbocharged Four may be fine for drag-racing your Civic on a Saturday night, its not a good choice for a large SUV that has to haul heavy loads.



RE: ignorance
By DocDraken on 2/8/2007 6:52:58 PM , Rating: 2
quote:
The OP mentioned a 4-cyl engine matching a V8 in peak power output, and then (incorrectly) assuming that the engines had equivalent performance. In this case, the smaller engine compensates for its lesser torque by a higher rpm peak on its peak power curve. So though the horsepower is equal, the torque is less.


LOL. No, I wasn't assuming anything. I'm talking about real engines that you can go out right now and buy in a car.

Does 260 HP and 258 ft.lbs. at 1900RPM and then a plateau all the way to 4500 RPM from a 2.3L turbo 4 mean anything to you? How about 340 HP and 376 ft.lbs. also from a 2.3L 4-cylinder turbo engine with a couple of bolt-on mods? Got anything clever to say now about the small engine having lesser torque? No, it's all about airmass.

Modern highly efficient engine design doesn't seem to be your thing. You sound more like a pushrod kind of guy.

As for what engines I'm talking about, well if you don't know them, try Google.


RE: ignorance
By masher2 (blog) on 2/8/2007 7:26:14 PM , Rating: 1
> "Modern highly efficient engine design doesn't seem to be your thing...."

Maybe not...but every automotive engineer in the world agrees with me. Which explains why you don't see any fullsize SUV or heavy trucks using your nifty idea of four-cylinder turbo gas engines.

> "Does 260 HP and 258 ft.lbs. at 1900RPM...from a 2.3L turbo 4 mean anything to you?

Saab 9-5 Turbo Sportwagon? You're right, I had to Google to find it. This is your example...a car that actually gets considerably less MPG than the Toyota Highlander, despite having a smaller, lighter platform. Guess that turbo-four idea wasn't such a good one after all.

I think its plain who doesn't understand engine design.. A small turbocharged gas engine is ideal for some applications. For pushing heavy loads, its a poor choice. Read up a bit on why...its really not that hard to understand.


RE: ignorance
By iNGEN on 2/8/2007 3:48:06 PM , Rating: 2
quote:
You forgot a little thing called torque. A turbocharged 4-cylinder may have equal horsepower, but its still going to have far less torque.


Although your comment about thermal loss was spot on, the above comment about torque is factually inaccurate. For a given airmass the greatest torque produced from a traditional reciprocating engine is achieved with the greatest pressure. There are practical limitations that make my previous statement a generality, but within the manufacturing and operating constraints of normal production cars it remains true.


RE: ignorance
By masher2 (blog) on 2/8/2007 4:19:30 PM , Rating: 2
> "the above comment about torque is factually inaccurate. "

Err, no its not. A four-cylinder engine is going to produce considerably less maximum torque than horsepower. The larger the engine, the lower the peak in the power curve, and thus the more torque produced per horsepower.

Need some examples? Honda S2000 DOHC-VTEC 4-cylinder engine. 240hp...but only 153 ft-lbs torque. Compare that to GM's V8 LT-1 F-body engine. 285 peak hp..but 335 peak ft-lbs. Only 20% more horsepower...but over twice the torque. Look at an even larger diesel engine, where a 400 hp engine might have as much as 800 ft-lbs of torque.

This is a basic factor of engine design. If it produces the same power at a lower average rpm, it's going to have higher torque. It's just basic physics.


RE: ignorance
By DocDraken on 2/8/2007 6:40:24 PM , Rating: 2
What part of "turbocharged" don't you understand? Your example is a naturally aspirated engine that is infamous for being a gutless wonder that has to be revved like crazy to get any power. The complete opposite of a turbo engine.

Yes, you might ultimately get a bit more torque with more cubic inches, but HP is still what wins races, and were you to compare 2 cars with 300 HP and 280 ft.lbs. and 285 HP and 335 ft.lbs. the first would be faster all other things being equal.


RE: ignorance
By masher2 (blog) on 2/8/2007 7:09:25 PM , Rating: 2
> "Yes, you might ultimately get a bit more torque with more cubic inches, but HP is still what wins races"

You're still missing the point. People don't buy trucks and SUVs with V8 engines to "win races". They want hauling power, and a little extra acceleration off the line. By the time the average turbocharger has kicked in, they usually don't need the power any more.

Also, don't forget that turbocharging lowers the fuel efficiency of an engine and-- even excluding the additional complexity of the turbocharger itself-- results in higher running temperatures and thus more frequent maintenance.


RE: ignorance
By DocDraken on 2/8/2007 7:22:33 PM , Rating: 2
quote:
They want hauling power, and a little extra acceleration off the line. By the time the average turbocharger has kicked in, they usually don't need the power any more.


LOL, so you're saying that people change gears before 1800 or 1900 RPM? And no, modern turbochargers don't have any lag to speak of unless we're talking huge aftermarket turbos. Spool up is pretty much immediate. Of course some models are exceptions. Notably the Subaru WRX has a bit of turbo lag.

quote:
Also, don't forget that turbocharging lowers the fuel efficiency of an engine


Say what? You get energy from exhaust gas that would otherwise be wasted, and you get V8 power with 4 cylinder mileage. Please explain how that is lowering the fuel efficiency.

quote:
even excluding the additional complexity of the turbocharger itself-- results in higher running temperatures and thus more frequent maintenance.


If it's properly built there is no difference in reliability between a turbocharged engine and naturally aspirated engine. It doesn't need more frequent maintenance either. The engines I've mentioned in this thread routinely go >300K miles on original internals and turbos. Oil changes don't have to be more frequent than 5000 to 15000 miles depending on use (of course, a good fully synth oil is required). As for higher running temperatures - well you have heard about using different size radiators and oil coolers for different engines, right? Water and oil temp is not higher than in any other engine.


RE: ignorance
By masher2 (blog) on 2/8/2007 7:49:26 PM , Rating: 2
> "Please explain how [turbochargers] lower the fuel efficiency...."

Sure. A gas engine is a heat engine, and is thus limited by the basic Carnot efficiency equation which is driven by the delta of input to exhaust temperature. A turbocharger increases waste heat, which lowers efficiency. That's a basic element of turbocharging-- you boost the power-to-weight ratio, but you lower efficiency somewhat as a result.

> "If it's properly built there is no difference in reliability between a turbocharged engine and naturally aspirated engine..."

Again, untrue. Even if the engine is built to withstand the higher temperatures and pressures, you have the simple fact that you have more parts to fail. A turbocharged engine is more complex, and thus has a lower reliability.

> "It doesn't need more frequent maintenance either..."

The automakers themselves disagree with you, as most recommond more frequent oil changes on turbocharged vehicles.


RE: ignorance
By DocDraken on 2/8/2007 6:35:30 PM , Rating: 2
Whatever you want to call it, the fact remains that a V8 with the same amount of power as a turbocharged 4-cylinder will use more fuel.

As for your misguided attempts at explaining torque, it's obvious you don't know a lot about turbocharged engines, as their typical characteristic is lots of torque low down. Your response reflects a common misconception.

There are several examples of turbo charged 4-cylinder engines dating back as far as the early nineties (225HP and 252 ft.lbs. already at 1800 RPM and plateau up to 4000 RPM.) Or how about 260 HP and 258 ft.-lbs. @ 1900-4500 RPM.

So your notions about "far less torque" from a turbocharged 4-cylinder is pretty dated.


RE: ignorance
By exdeath on 2/9/2007 12:09:39 PM , Rating: 2
Couple things I feel I should jump on here.

You can make any engine as powerful as you want. It doesn't matter how many cylinders. It all comes down to money. In the end, using the same leading edge materials, etc, a I4 is half of a V8 and will always be half as capable, a V twin will be half as capable as a I4, etc.

Case in point, look at the pro level nitro methane drag cars. Blown 8L V8 = 4000 HP. Blown 4L I4 = 2000 HP. Blown nitro methane v-twin drag bike = 1000 HP. Half the cylinders, half the power, half the size, etc. The limit is in the materials, and at this level of performance, you have the same materials in both engines allowing for the maximum power per cubic inch of air at the highest PSI possible.

The idea that a V8 has more friction is bogus. Its not like those added pistons are along for the free ride, they bring their own power with them to make up the difference. What you mean is that putting a V8 in a car that could get by with a turbo I4 is a waste of the V8's true potential over the I4 and simply lazy engineering. It's also marketing.

For people that don't think a I4 can make torque, look at this:

http://atsracing.net/spoolmaster2200.JPG

Thats 375 ft/lbs of torque at 3575 RPM from a 2.0L.

Torque is about airflow management throughout the RPM range. Maximizing air mass flow for peak horsepower will rob any engine of low end torque: Take a look at the high revving Ferrari V8s, lots of horsepower, and way less peak torque.

More displacement is always going make more power, just like more boost, more of anything that can flow more air. But there is also a limit to how large your cylinder bore can be before you lose precise control over ignition and flame front expansion, control that is critical to maximizing the power extracted from the mixture. It takes balancing of many many factors.

If you can turbo a I4 to run like a V8 with I4 mpgs, you can also turbo a V8 to run like a V16 with V8 mpgs. All that really matters is how much air you are pumping through the engine. When you reach the limits of boost, you can add more cylinders. When you reach the limits of how big your cylinders can be, you stuff more air into them with boost.

In the end its all the same goal: Burn as much air and fuel as you can without destroying the engine. With the best materials on Earth, you should realize that every engine configuration known to man would eventually lead you to reach a constant value. This value is a result of the maximum air/fuel density, maximum pressure, maximum heat, and ultimately a maximum power per cubic inch possible given the materials and the fuel used.

So once again, V8 = 2x I4, all else held equal. Of course you will see highly engineered I4s making the same or more power than under engineered V8s, most likely because someone got lazy or simply decided it was more cost effective to throw in a simpler V8 at half its potential to get the same power as a highly engineered I4.


As for reliability, that is also bogus. Forced induction does not increase the peak heat or cylinder pressure. What you get is a more constant plateau of pressure throughout the entire power stroke instead of a peak and a sharp drop off, but its still well under the peak. You get continued constant expansion throughout the entire power stroke instead of the top, particularly toward the bottom when the rod and crank are at 90 degrees and the work advantage is highest.

Yes this generates more heat, because you are getting more power. Basic physics, and this applies to any engine. IF you have a 2.0 I4 making the same power as a 4.0 V8, that I4 factory radiator isn't enough anymore, its going to need the same radiator capacity as that V8. Again, basic physics.

As for hybrids... the engine in a hybrid has nothing to do with the MPG. The car design itself is more to do with it. You can't stick a Prius engine in a Camry and get 60 mpg. The design of the car itself as a system has far more importance than the engine. The Camry would have to be shaped like a Prius, made out of plastic, carbon, and aluminum, and not have power this power that power everything robbing power from the engine via hydraulic pumps, etc.


RE: ignorance
By exdeath on 2/9/2007 12:16:51 PM , Rating: 2
Oops, that graph shows 375 ft/lbs at 3500 RPM.

Whats a LS1 put out, 300-400 ft/lbs at 4500 RPM?

This isn't a X engine is better than Y engine comparison, just a simple illustration. You could turbo the LS1 and build it with the same materials and make twice the power as the I4.

But the point is, they DONT. They use an engine with too much potential for their power goals without using that potential, and as a result, you pay the price associated with a bigger engine.

Its the same reason gas turbines are not used in cars. They are way more efficient than piston engines, but only at sustained power levels far more than what is needed for a car. To nerf it down for a car would get crappy mpg and all that draw backs of that type of engine with none of the advantages.


"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -- Isaac Asimov

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