Just open the car main cfg and change de coordenates of the phys like this
body 0.000 -0.114 0.117 0.000 0.000 0.000 120.000 cars\racers\Prime_data\meshes_phys_chassis_cockpit.scx ;0x0000000D
body 0.000 0.114 0.117 0.000 0.000 0.000 120.000 cars\racers\Prime_data\meshes_phys_chassis_cockpit.scx ;0x0000000D
Some cars you need to do it on the doors, bumpers, etc