A big -1 from me.
This is the most useless suggestion i have ever seen. If you don't want your car to be respawned, just get in and wait until the respawn is over. Considering the current player count and how badly optimized the server is, this might cause a lot of fps troubles, especially for those with low end pcs. Additionally, some people will abuse this feature, leading to numerous adminjails. Just think about it, you're suggesting adding more rules to a server that already has a lot of rules, just to prevent abusing an unnecessary feature. Do you want to make the server unplayable by adding unnecessary rules?