Spent a while doing this yesterday for my program! Anyway, here are the idle values if you want them. It's in C++ but at least you won't have to go through each car to get them!
char Cars[19][4] = {"XFG","XRG","XRT","RB4","FXO","LX4","LX6","MRT","UF1","RAC","FZ5","XFR","UFR","FOX","FO8","BF1","FXR","XRR","FZR"};
int CarIdleRPM[19] = {966,966,970,971,969,955,955,976,978,975,966,1447,1452,1908,1900,3652,1437,1437,1448};