If someone steals my car and sells it can i call the insurance company to replace it?

Was finishing a long GTA Online session with several crew members and we all stole a car to sell to LSC before logging off. One of the guys jumped in my personal car and drove off before i asked him not to sell it.

If he sold it, would that mean i lose the car or can i just call up the insurance company to replace it? If not, does he get more money if i add mods to my car?

You can't sell other players' vehicle(s). And you can set your personel vehicle to lock to everyone, yourself, friends, crew, crew + friends, and no-one. To change your vehicle's lock setting, go to: Interactive Menu >> Scroll down to Vehicle Access >> Select your setting.

Look people can not sell personal cars when they go up to Los Santos Customs. A message will pop up on their screen saying something like, "You cannot use this car belongs to STYZ Westcoast" so they can't enter Los Santos Customs. Or just for ps3 hold select for xbox360 hold back and go in inventory and change vehicle access "no one" and they get kicked out of the car.