Crank vs. rear wheel

I don't think there is any set percentage for this, it could vary from vehicle to vehicle even if it's equipped with the same trans and differential. It's all going to be in how it was setup and what modifications were done. For instance if you up the line pressure in an auto trans it's going to eat more horsepower. The torque converter is going to factor into this as well, pinion turning torque is going to be a factor as well as the lubricant used in the differential and/or manual trans.