which transmission is better with performance and gas mileage: auto, manual or auto-manual?

Manual transmission are usually cheaper, more simple and give the driver more control. But a manual gearbox will not always perform better. Many modern automatic, semi automatic, automated, and twin-clutch transmissions actually provide better performance than cars with a full manual. The automatic transmission is not what it was 30 years ago. They shift more correctly and faster than even the best driver could do with a full manual. Why do you think most high-end performance cars offer no full manual option? Ferrari 458 Italia? Ferrari Enzo? Mercedes SLR? Nissan GT-R? Bugatti Veyron??? They're all cars that are insanely quick without a full manual. It's become very difficult to find a big name super car that offers only a manual. And it's not just better performance that you'll find. many modern auto transmissions have just as good or better fuel economy than a manual trans in the same car...

E: The Honda Civic

26 / 34 mpg Manual

25 / 36 mpg Automatic

The Infiniti G37 Coupe

17 / 25 mpg Manual

18 / 26 mpg Automatic

And many others are like the Civic and G37.

Manuals do (if properly driven). Automatic transmissions rely on a fluid coupler to connect the engine to the driveshaft. There is always some sort of slippage resulting in wasted energy. A manual transmission is directly connected via a clutch which offers no slippage unless it is defective. It's the fluid coupling (called a "torque converter") that is the culprit in most automatic transmissions disadvantage in fuel mileage. There is slippage when an automatic changes gears. Once you are under way, most modern automatics will lock the torque converter so that there is no slippage, but the control computer is usually programmed so that the slightest grade causes it to unlock, and in some conditions, to downshift. All else being equal, staying in the highest gear practical gives you the highest fuel mileage. There are two main reasons. -Friction is more a factor the faster the engine is running. Keeping it in a high gear lowers rpm and thus friction. -Your internal combustion engine is an air pump. It sucks in air to mix with fuel to burn, and then exhales the products of that burning. A higher gear requires a bigger throttle opening to maintain speed, which is less restrictive. Let me 'splain The larger the opening letting air into your engine, the less work it has to do to suck it in. Try breathing just through a soda straw if you want a demonstration. It might seem that a wider throttle opening would burn more gas, but it does not. At the same speed you burn the same amount of fuel to overcome the drag of the wind, friction in the drive train, and rolling resistance of the tires. The only other factors are internal friction in the engine, and intake restriction, both of which are optimized in the highest practical gear for conditions. A manual transmission gives you absolute control over what gear you are in.

the answer is that a manual is better. if you are using an auto-manual in manual mode, it would be the same as a regular manual. if you use an auto-manual in automatic mode or a hybrid (eg switch back and forth depending on the roads), it will be worse or at best the same. make sense?

manual is wat better for peformance and fuel mileage. autos shift slower and not always when you want them to, auto manals are the same thing , they delay the shifting and shifts are not as quick, ex if your in 5th and want to drop to 3rd it could take 2 full seconds for a auto manual and a auto you need to slow right down, with a manual you just pop in in gear and go . your friend is wrong , he prolly just cant drive a stick and is jelious.

i can squeeze out an extra 5-8 mpg with my manual trans in my mustang, it allows me to short shift and keep the rpms low to save gas and perf. wise have more control over the car through the rpm range