[SuperSound]

Originally Posted by Denis

im not arguing about this at all, but how do we know the current numbers are more towards 10% as opposed to the 20% we all used to use? are we just assuming greater efficiency or have their been studies to prove it?

Well for one look at the fact that all of the cars lately (Dodge, Ford, GM, etc...) are using SAE ratings and all show more power at the wheels than the 20% assumption which dates from decades ago. This means either all are underrated the same (which is BS) or the drivetrains (not just transmissions) have become more efficient. So it's reasonable to assume you can't assume a figure for old 3 or 4 speed lockup converter transmissions still holds true for these modern 8+ speeds fast shifting autos.

When you think about CAFE it's obvious the auto industry needs their engines and transmissions to be more efficient to meet those MPG targets. They have been making steady gains but it really wasn't obvious until these new 8, 9, and 10 speeds autos started showing up. The technologies they are using to get those fast shift times is related to the drop in parasitic loss between manuals and autos. Granted the additional gears are contributing too.

I'll have to look around but there was an in depth tech piece on the ZF 8 trans speaking to it's improvements in power loss. Maybe someone else can post some evidence.