So, first Idea is ACTUAL AIRBAGS. I know it would be a crap ton of work, but i t would be SO DAMN AWESOME to have in the game. Then i would suggest actual visible Coolant and Oil Leaks (Im gonna get to them in the next Idea), with that i mean just a trail behind the car when the Radiator or the Oil Pan is damaged. (As i said, next idea.) THE LAST IDEAD: OIL LEAKS! When you do a big jump or something and your car scrapes on the front becasue of the suspension reching its limit, the oilpan should get damaged.
I don't want to be that guy.... but for once I am going to be that guy. Both airbags and fluid leaks have been discussed numerous times in the forums. If you use the search bar you can come up with plenty of reading material.
