I'd take a manual over automatic any day. They are more efficient on fuel (except for a few cases with the very latest transmission technology), they're more fun to drive and the driver has a ton more control over the car.

Quote Originally Posted by I'm my own MILF View Post
Modern automatics are extremely precise about when they change gears, as Ouch! said. They'll change to be efficient with gas as much as possible. certainly better than all but the most expert Human. Also yeah, less work to perform the same task = more efficient, that's pretty much the definition of efficiency.
Changing gears in a manual is mechanical, using energy from the driver via the clutch and gearstick. In an automatic, the only place that energy can come from is fuel or battery (which is charged by fuel anyway), not to mention the computing power required to stop the automatic transmission from intrusively shifting gears and also to maximise the fuel economy. That's why autos are inherently less efficient on gas. If a driver's driving a manual such that fuel economy is less than it would be in an auto, then they aren't doing a very good job at driving.