According to the Indian Motor Vehicle (IMV) Act , the transferor has to intimate the Regional Transport Offices (RTO) within 14 days of the transfer of ownership. Similarly the Act also instructs the transferee to inform the RTO about the change in vehicle ownership and produce all the required documents within 30 days of the transfer.

2) The transferor is required to fill Form 29 while the transferee is required to fill in the Form 30,

3) send a letter to RTO where your car was registered informing them that you have sold the car and handed over original papers of car to purchaser

4)if the car is involved in some major accident or stolen and used for some anti-social activities police will file complaint against you as your name is reflected in the RC book

See you have to file a police complaint and further send copy of the complainant along with the other documents such as delivery note with a covering letter to concerned RTO's.

The police on complainant may help you on this and RTO intimation may safeguard in case of any mishap in future.

You can make complaints in Missouri RTO and Delhi RTO. Plus send letter to Insurance company without your identification how they have renewed the policy etc. Kindly barred the insurance policy of car. 

File FIR of cheating and theft.After sale of car but ownership is not transfer, buyer cannot renew insurance in your name. Illegal act of impersonation.

Till ownership do not transfer, you are not absolve from liability - eg. policy lapsed and accident, you have to compensate injured.

If showroom is closed, send legal notice to branch and that person. 

You should issue a legal notice to the buyer with a cc to Regional Transport authority and police station(where the buyer lives) to change the ownership of the vehicle.

Police station will seize the vehicle immediately as the buyer has not changed the ownership details in RTA Office.

Regional transport Authority is also empowered to seize the vehicle if police do not act.

1. File an Police FIR, about the current status of the Car being used without your permission and false insurance in your name. Ask the Police to impound the Car. Provide all the relevant documentary evidences you have to the Police. Create documentary evidence of the Police FIR.

Since the car has not been transferred to the buyer's name yet, any problem that may arise shall become the current owner's liability and not the buyer's.

Therefore to avoid any unforeseen incident as anticipated, you may better contact the said person and offer to cooperate with him to transfer the car to his name by following the requisite procedures as mandated in law.

Without taking any action in this regard you may have to face legal consequences in case the car meets with an accident i=or it is involved in any illegal activity and being held by the police or law enforcing authority.

If he is using the car registered in your name you'll be held liable in case of any offence or accident. Give a legal notice to him and in case he does not respond then file an fir against him.

Regards 

1. Send a written complaint to RTO Delhi and Mussoorie that car was sold and new owner have not registered the car on his name.

2. RTO of Mussoorie and Delhi will send the details to traffic police department for taking the vehicle in their possession.

3. Send a legal notice to new owner and dealer for transfer of RC on new owner name. 

4. You can also send notice to Insurance company intimating about vehicle sale.