Written 40 or 50 years ago - a virus kills off all in the world except genius IQ people - two characters enter the picture: one is a teenage boy who is a world class pianist; the other is a girl of similar age who is in a coma for a few weeks. They leave and try to get to the West Coast, I think, and invent a vehicle that can ride railroad rails. That's all I can remember. It was excellent. The boy is full of real groaner puns.
The author was introduced as the next Heinlein (along with a lot of others, I suppose). I don't know anything more - if he became famous, died young - just dunno.