Check out this link:

http://www.teamwir.com/Car%20Math.htm

The HP estimates are a little off; I think this is due to it calculating rear wheel HP. It's still cool to play with the numbers. It shows you where you should be, could be, or want to be.

 

Neat. They're pretty close about the whp, but not the hp itself.

 

The calculations are said to be for rear wheel HP.
If I am not mistaken, rear wheel HP in Tsx = 0 (unless you are driving in reverse gear).

 

If this is accurate for rwhp, then rwd really does lose substantially more than fwd from crank to wheel.