|
the two big differences between manuals and autos on the EPA test are:
Manuals have prescribed shift points (ie you shift to a certain gear at a certain speed) which don't really take into account gear ratios so short gear cars end up running at higher revs and are less efficient. Autos can use their own shift strategy
the gear ratios are much long on the auto (for the auto 4th is a straight through where as it is in 5th for the manual) this allows the higher speed portions of the test to still be run at low revs. This also means that the manual will be faster on a track as it can keep at peak revs for power better.
as mentioned above auto boxes have much lower losses than before so now the extra inefficiency in terms of drive train losses is less than the fuel savings from running the engine at a better BSFC point.
This is also the main reason why in Europe manual gearboxes are being dropped on a lot of sports models because of the fuel consumption legislation (BMW M5, Audi RS4, Ferrari, soon to be Porsche 911 etc)
|