Does anyone have any real information about the power consumed by C-6 and C-4 transmissions? That is, as opposed to a manual.

I ask, thinking of building for milage.

 

Maybe a 5% penalty for the automatic.

Building for mileage....only an overdrive lockup torque converter automatic is going to compare favorably to a well driven manual with the right gears.

Of course, with the same axle, the OD auto will hose the non-OD manual, unless you already have 2.50 gears or something the auto won't pull in OD.

Many factors here, mostly the total weight of the vehicle, the aerodynamics, and how it's driven. Then we can quibble about the transmission.....

 

C6, I'd guess it eats around 30-35hp. The C-4 takes less, but it's also not as strong of a transmission as the C6, which is pretty bulletproof.Neither are going to get great mileage, as neither are OD. If you don't want to mess with computer controls, you might want to see about putting in an AOD trans, it's a 4-spd OD, not bad for light duty. If your not too worried about performance/towing capacity, that would likly be your best bet, but it depends greatly on the engine and vehicle.

The AOD-E is a newer variant, electronicly controlled with some other improvements, would require an aftermarket computer to operate.