Dear Parikshit,
Yes Old car NCB can be transferred to new car.
I can share with you a ground level practice which is what done by some dealers who exchange old car is that they issue in
1. Dealer Sale Letter (Delivery Receipt) - although delivery not taken by dealer but given in good understanding for NCB issuance purpose - for same what they do is issue a letter with stamp and sign then a photocopy issued to customer for NCB issuance purpose.
2. RTO Form 29,30 - Filled with stamp of dealer and customer signed, again a photocopy issued to customer.
Now
1. Insurance Policy
2. RC Copy
3. Dealer Sale Letter
4. RTO Form 29,30 can be sent to Insurance company through Email
and ask them for transferring NCB to other car / new car whose
> Invoice copy (is what needed by them from True Value)
> Car RC Details
> Letter request for transfer of NCB from Old car and cancel policy to this New Car as purchasing.
So Insurance company executive will process same internally and transfer NCB of Old car to this new car as purchased in New Policy Quote.
Kind note that in this process the existing Policy will be deemed to be cancelled or if dealer needs active insurance of old car then he has to pay NCB Difference of left out period (so you need to communicate to dealer pre hand for same)
Hope should help !!