Unfortunately this in not wotrking for me. Car does not even appear in the spinnerYou sure can use Reiza physics in your mod. You just need to direct the cars to the physics in the veh file. The F1 2005 mod is a good example of how to do it. See the entries below in bold.
HDVehicle=F_V10\F_V10.hdv
Graphics=BAR.gen
Spinner=BAR_Spinner.gen
GenString=BAR03
Cameras=BAR_cams.cam
Sounds=F_V10\F_V10_sound.sfx
HeadPhysics=F_V10\F_V10_headphysics.ini
Cockpit=BAR_cockpitinfo.ini
Upgrades=BAR_Upgrades.ini