rF Classifications

I've been running F3's mainly but I want to do some tintop night driving.
My problem is which class matches other classes? I want all cars to have
similar performance if possible while still using upgrades and different car
models.

Anyone have any idea of which classes of cars are similar performance or
where I can find this info? What do all the different types mean? Whats
different between GT1 and GP1? or A type vs M type? This is what I despise
about fantasy cars. I know the difference between a vette and a VW but
what the hell is a howston gp1 or a Hammer gt2?

Mitch