/c repair is alrdy a cmd used by payNspray
The thing is some ppl like me are ubsesive compulsive and like to have there car look shiny all the time
maybe you can set parking lots as the only place or prop
theres also the possibility of if you're wanted "Cannot repair car""not enough time"
not enough time meaning the cops would get you b4 you repair
of course it would have2b instant because wating 20 minutes to repair is dumb but as far as rp it makes sens
as for the spawns I think ppl should b able to control where cars they own start off
even limiting it to you're prop with something similar to /c spawnprop
