It would be great, but as it would almost always be pure DM it should be enabled in LV only. I don't think the script should be modified like that.. Also, if your vehicle blows, you'd need a mech to repair it again, except if it was a spawned vehicle, but you do not get spawned ones anywhere except bikes.
NO!Why?simple if you add it to LV it will go to install the bomb there and use it out, also everyone will be complaining about that "noob with explisive car, hhahah noob, noob with nades, as the do actually" Also I want to ask, will you sacrifice your car to kill someone that will respawn in some mins later?