I beat the game with a few cars that may help you.
Grip Audi54 maxed out
Drift Nissian 350z maxed out
Drag Dodge charger maxed out
Speed 911 turbo maxed out
I did use the cheat unlock all things to get 90,000 + each time you enter the game. You 1 go to carrer 2 go to code entry 3 enter unlock all things 4 enter any race 5 exit the race 6 go to the garage 7 you have 4 new cars 240sx colbalt gto viper 8 sell them all you get 90,000+ hope ot helps.