[usrusr]

The correlation between efficient driving and aggressive driving is far from perfect. The "pulse and glide" method from the wikipedia page linked in a sibling comment would seem quite aggressive for example and on the other end of the scale, I have often seen "moving roadblocks" running their engine at RPM far too high for efficient cruising (e.g. when people drive a manual who are afraid of shifting).

[dsfyu404ed]

Hauling ass from one light to barely run a red on the next one is a hell of a lot more efficient than seeing the yellow, accelerating like an old man, coasting for awhile, braking to a stop and idling for several minutes.

Every time you touch your brakes you're throwing away the energy it took to get to that speed. Coasting through off ramps at highway speed is good for the environment.