1. The ownership to a vehicle flows out of the registration certificate thereof. You continue to remain the owner of the vehicle for all legal and practical reasons unless and until the registration certificate of vehicle has been transferred in favour of the buyer.
2. If tomorrow he runs a person down under the vehicle you sold to him and then runs away the police will launch a manhunt to arrest you. Furthermore, you will be liable to compensate the victim's family members if he dies or the victim if he survives.
3. At the time of selling your car, you would have obtained a delivery receipt from the buyer. This receipt is proof of your having sold the car to the buyer at a consideration, but this is not proof of ownership of the vehicle.
4. You must be having copies of the forms and the R.C. Book which were required to be executed by you while you had sold the vehicle. It is your legal obligation under section 50 of the Motor Vehicle Act that you send a registered letter to the concerned R.T.O. informing that you have sold the vehicle to such a such person ( give his address and telephone contact number) and have handed over the R.C. Book to such purchaser, in which event when any traffic offence is done by him the police will check on with the records of the vehicle from the R.T.O which would reveal the new name of the purchaser. Meet an agent who does such R.T.O. related work.