So for the wreck system, I have a few suggestions for it:
(If not added already), then add a takedown system for players without power-ups. Basically:
If you land ontop of a vehicle after dropping from a certain height, that player is automatically wrecked.

(Singleplayer only or against AI if you add it): Slowmotion upon wrecking (yes, most of these features come from Asphalt 8)

And for a general suggestion

A sort of trick system where if you hit a button in air, you gain a boost upon landing.