I gotta agree, 750 Watts to cruise @ 70MPH is hard to believe... Jze.. get an eagle tree and test it out.. and again, there are just way too many factors..
While I agree somewhat with ZPB that it probably doesn't take 100A to "cruise" an emaxx at 70mph, the current would still be substantial due to wind and drivetrain drag.
Plus, due to radio range issues, you won't have very much cruising time at 70mph unless you are driving a real car alongside it.