[stulec52]

I was thinking about this as a similar topic came up on TamiyaClub.

I also thought which car made the biggest jump in performance over everything else when it came along.

Also you asked for era, not year, so for me there are 3 cars that set the bar just a little higher when they came along, and therefore are the best of the era for me.

CAT XLS - I was going to say the original CAT, but honestly it was so hard to drive, and even harder to build without breaking anything !
XLS made the CAT accesible to Joe Racer and kicked butt !
Optima Mid Custom Special - I know it wasn't really the car that pushed the bar higher as such, but it was the final refinement of that model which was such a great car.
and the number 1 position goes to:

RC-10.
it was better than the 4wd cars of the day !
Just THE car to have if you wanted to race.