Engine Capacity and Fuel Economy:
http://en.wikipedia.org/wiki/Car_engine#Engine_capacity
A bigger capacity engine does impact it fuel economy. So no doubt their engine do use up more fuel, compare to other European engine with the same horsepower but less capacity. 8.3L V10 Viper engine to produce 510hp, Mercedes got a little more than that with a 6.2L V8. Corvette 7.0L V8 for 500hp, BMW got that much out with a 5.0 V10.
You know, you say that, but so far, the only proof I've seen is that our big, "ineffecient" engines provide superior fuel economy than and equivelantly powerful Euro engine. When your engines provide the massive amounts of torque some of our v8's do, you can gear them down to the point where you'll get excellent fuel mileage. Those stressed out Euro engines can't do that. It seems the Japanese have trouble as well.
Here's something to ponder
Why is it that the super light Lotus elise, which is also just as Aerodynamic as anything else, with an "effecient' japanese engine, only able to get fuel economy numbers with your standard issue Honda Accord? It's got significantly less weight to lug around, it's only using a 1.8, that by your definition is efficient, and yet it gets 35mpg...
I've heard the Elise can do 35mpg, but I've only seen evidence that it's only meeting epa numbers of 27 highway...something a 7 litre z06 can do with an extra 1k lbs to lug around (infact I've seen more than 3 magazine get 28 with cruise control on). BTW, I'm only talking about the toyta 2zz powered Elise, as that was the one available in the US.
Oh one more, the lighter just as Aerodynamic Lancer Evolution's with their high tech 280hp turbo 4's with manual transmissions can't beat the fuel economy of 7 year older Chevy Camaro v8 with a 4 speed automatic.
And now some of you are talking about your Turbo charged engine. Turbo charged engine of course it does harms the fuel economy. Why not compare an Naturally Aspirated engine to a Naturally Aspirated engine. Probably at my first post I shouldn't compare the Viper's engine to the Veyron. Sorry that's my bad. And I shouldn't call European or Japanese engine more efficient. They are just more sophisticated.
Sophistication costs money. And ever notice how massive a Euro or Nissan v8 is compared to a small block? Toyota has a 4.3 Litre aluminum v8 with 4 cams and VVT on it, it's physically just as big as a small block, and you can't get any more displacement out of it.
I'm sure you'll be delighted to hear GM is working on a new small block with twin cams...still pushrod activated valves though. This way they can impliment VVT while keeping the engine size to a minimum.
There is another thing to consider about a bigger capacity engine. A bigger heavier engine compromise the handling, especially in a front engine car. It makes the car nose heavy. It spoils the handling.
Adding turbo's to a car adds just as much, if not more weight. Ever see how heavy a Honda h22 prelude engine is? An SR20det (with turbo/ic connected) weighs a few pounds less than an GM LSx engine. Of course the SR20de(t) also weighs 30lbs more than the solid cast iron CA18de(t) it replaced...
Another comparison would be the Jag v12's. Much newer design than the GM big blocks v8, which hasn't had a significant update in probably 45 years now. Jag v12 is all aluminum and available in 5.3 or 6.0 litre's (racing versions when upto 7.7, and if you push your luck it will goto 9), the Big Block v8's from GM are solid cast iron, and from the factory came in 7.0 upto 9.3 litres. Both engines are about the same weight.
Honda's "high-tech" and "modern" 4 cylinders are marginally lighter than the Buick 215 v8 (designed in the 50's!). The Brits will know this engine better as the Rover V8. Yep, it's our design, American's gave it up, unfortunately.
I could continue, but I think I've made my point.