It doesnt matter how many hp you make per liter. It matters how much hp you make. And I'm very curious as to the rationale behind japan's tax on displacement. If you notice, the LS6 V8 makes the same gas mileage as this car's V6 and has twice the displacement. Sure, the S2000 might have some kick when you rev it up to 6 grand, but your redline is only a few thousand above that, making your powerband very narrow and very inaccessible. Thats why I prefer the V8, which can turn serious torque at low rpm and drive you all the way to the redline. Wider powerband: much more useful. About torque, torque is the amount of twisting force the engine can apply to the wheels, it determines your acceleration. Horsepower is a measure of the engine's ability to do work over time. Thus, horsepower determines your engine's ability to hold you at top speed, etc.