I was more into model trains that I was race tracks, but my brother was really into racing. He and his friends were always modding their cars, trying to end up with the fastest one.
There where two basic kinds of tracks that I remember, slotted and not slotted. The ones that were not slotted you could change lanes with the speed controller. They even had pieces of track that had an HO Scale railroad intersections so that you could run your train across the racing track. The only downside was the cars were really big in comparison to the train. But the concept was still cool.

Aurora AFX Race Tracks from 1975 a
(My car was the 57 Nomad but mine was blue.)

Aurora AFX Race Tracks from 1975 b
There were a lot of different trace tracks in the 70s so I will have to covering them over several posts. These are some of the race tracks that I remember seeing commercials for. The Aurora “Golden Gate Road Race”, “Double Dare Devil Road Race”, and “Challenger Road Race”.