Speaking of torque (i.e. no wonder the E90/92 M3 is so fast...)

[clyde]

Originally Posted by John V

And fuel economy is very closely tied to engine RPM (and weight, and to a much smaller degree throttle position) so yes, the BMW gets worse mileage.

It may be splitting hairs and going in a different direction than you're talking about, but fuel economy is also tightly tied to throttle position. If you are traveling at a specific RPM with a constant throttle position, your fuel efficiency will be much better than if you rapidly alternated between wide open and closed throttle positions. If you jump on and off the throttle, obviously, the RPM won't be static, but if you do this over a set distance and turn the same number of revolutions and have the same average throttle position over that distance as the constant, you'll use a lot more fuel (how much depends on lots of variables).

How big or small the difference is relative the addition or subtraction of 500 pounds of load or 500 RPM...