I exceeded 40 mph drafting an RV on a level arterial road. It had turned off the same side road I was on, and because it accelerated gradually and there were no road junctions on the stretch ahead, i.e. I was pretty confident it would maintain speed, I kept up with it until we reached an incline.

I don't think I would do it again, since a bike doesn't brake as well as most motor vehicles. But it was fun just to have tried it once.