I thought we were talking real world though. Most places where the speed limit is 35 MPH, there's not enough distance between stops to to cruise enough to offset to amount of fuel burnt by accelerating to get up to speed. Lower RPM's does not necessarily equal less fuel consumption. If the engine makes a big amount of torque in the lower RPM range, it will. More power doesn't necessarily mean more fuel consumption, either. It's all about combustion efficiency. On aerodynamics. Which is going to make the engine work harder? A van that's practically throwing a brick into the wind, or a sports car that's optimized to cut through the wind. To answer this, while driving down the road, open your window, stick your hand out. Start with the palm vertical to the ground, representing the van, then put it horizontal, parallel to the ground, representing the sports car. Which one makes you exert more force to keep your arm straight? Am I way out in left field on this?