Possible to have these infinite for car mods? I know once you use them they do not decrease in your actual save, but it would be nice for them to be infinite to enjoy mods better.
That would help. As an interim solution: pause & restart any 'freeplay' CarMODgeddon event and (regardless of what the Front-End APO indicator says), APO Upgrades on the AI cars & Player car will be reset back to stock. That way you can (at least) level the playing field with the AI.
EDIT: This does also apply if you Restart after the event has finished.
This might be different in future builds, but it works for now.
I find that the upgrades skew the default performance of the cars into unreasonable and sometimes odd levels, take for example the twister, fully upgraded engine it begins doing stoppies when you hit the brakes, like a motorbike, very jarring.