70mph roll? Who races like that, really? If you're going to race, take it to the track...and race from a stand-still like everybody else.
Come on, don't make excuses. That'll just make you look bad. If he wants to race, tell him that he's got you. If he's faster, he's faster. That's all there is to it. There are cars faster than yours, and there are cars faster than his. Race him regardless; you'll probably hang with him a bit more than he's expecting, and you might just give him a little respect for what a 2-ton land-yacht can do.