are manual transmissions harder or better on gas, or is there any effect on gas mileage at all?

Automatic transmissions usually sacrifice gas mileage or performance, if not both, because in some gears there is slippage (torque converter) and hydraulic pump. Although, advances have been make with automatic transmissions using lockup torque converters in higher gears, and many cars with automatics have taller gearing, so it is possible for them to get good "highway" mileage, but not the same performace or city mileage of a properly driven manual.

F1 and other racing has resulted in transmissions that work as easily as automatics and as efficiently as manuals, by using an electronic clutch/throttle coordinated with a manual shift lever or paddle shifters to electronically shift even quicker than most people could do manually. But they are expensive and not in mainstream vehicles.

They use LESS fuel. I drive an Eagle Talon turbo and my sisters drive Ford Focuses. They get about 27 mpg on the freeway and I get 30+. I have a manual and they have automatics. Manuals are more light weight, directly driven off the crankshaft and dont have to turn a torque converter. Autos are heavier, load the engine more, and have a torque converter full of fluid. There is come sort of pump inside auto transmissions also.

Manuals are better on gas.

manuals are def. better on gas...not by much but hey anything counts now that gas is so expensive!! I know this b/c i have a manual myself and b/c my father know tons about cars, so he told me this fact when i bought one!!

Manuals are better on gas seeing as they are simpler and don't rely on hydraulic crap to shift.

They are better on gas if driven properly.

manuels are easier.

much better

they use more gas!!