Manual Transmission?

If it is true then not by much anyway, I think it could be the efficiency in the gearing since an automatic gearbox pretty much uses 1 or 2 gears. While with manual you can for instance switch to a high gear whilst on the motorway to save fuel.

Manual will save you 1-3 mpg the reason it does is because the end ratio is slightly higher, you have less mass and parts to rotate and there is no slipage from a torque converter.

I guess it cause more effort on the engine, just like pulling a heavy load would decrease fuel economy because more strain is put on the motor. Just guessing, be easy on me.

I think it used to be more true than it is today. Automatics were not as efficient 20 years ago.

Even today a car with a small 4 cylinder engine will be noticably quicker with a manual transmission than the same car with an automatic.

An automatic transfers power from the engine to the transmission via a viscous fluid. It is also typically limited to 3 gear ratios plus an over drive. Most manuals have 5 or 6 gears these days.

A manual transfers power via the clutch and pressure plate. The pressure plate holds the clutch disk against the engines flywheel, creating a more solid connection. When you push the clutch pedal down, it pushes the clutch disk away from the engine and allows you to change gears smoothly.

The difference is a couple of litres per hundred km. especially around town it is very noticeable. With autos when you take off you dont have a direct drive as the torque converter(instead of clutch) slips until it reaches a certain matched speed of eng/trans. Obviously the auto has to work harder to transmit drive . Also the gears in an auto arent meshed, it is basically a series of plates forced together with oil pressure to transfer drive so it is not as efficient as a manual which is direct. check out power flow diagrams which you will find in any basic mechanic encyclopedia

The automatic transmission have hydraulics that need to be powered from somewhere – this power is tapped from the engine via the torque converter. This should be the main reason why automatic transmissions uses more gas than a manual transmission. On a manual you do not have any hydraulics (except for the clutch – and that is powered by the driver stepping on the pedal) and thus no other systems that will tap the engine power. The only losses in a manual transmission (gear box), are friction.

The latest automatic transmissions require much less hydraulic power and are thus much more effiecient than the older ones. The gearing on automatic transmissions are similar to manual transmissions these days and you also have the same number of gear ratios.

The other main factor that have a negative influence on gas mileage, is the added weight of an automatic transmission – they typically weigh about 100 to 200lbs ( 50 to 100kg) more than manual transmissions.

Everyone is making this way too difficult. If you’re not good at driving a manual, you wont get better gas mileage. If you are, you can get up to 5 mpg better. I get 5 mpg better in my eclipse than a friend of mine does in theirs which is an automatic. The reason it works is because an automatic is programed for best overall performance, not just best gas mileage. If the car was programmed to give you the best gas mileage, it would take off very slowly and have no power. With a manual, you have all the control. I can take of slowly at one stop light and get really good gas mileage, and the very next stop light I can take off racing and get horrible gas mileage. The cars computer that drives the automatic doesn’t know what you want each time. There are some computers that you can change for different situations. There is a menu that you pick from and the car shifts based on what you select, a car with that will get better gas mileage than a manual. It isn’t that the computer can’t shift for best gas mileage, it’s that the producers of the car make it good for overall performance.