I find the stock cars impossible to drive quickly. Too much understeer for me.
And learning how to setup a car in GP4 really isn't that tough. There are some excellent threads here on how to set up a car, and there is even a guide that was done for it over at GP4 Italia I think. It's well worth learning how to do, and for me increases the immersion factor quite a bit...
"There are some pikeys there at Turn 10 putting tarmac down - what do you think of that?" - Martin Brundle