I have an AZU Fourgonnette registered in France as 2 place (place for 2 people to sit). Can I apply to the prefecture to change this to 4 place and retain my existing registration number (which is the old format which I like). Fitting the rear seat is straightforward as the holes already exist and the insurance would need to be notified.
Also, I have changed the engine from 425 to 625cc. This will necessitate a change to the carte gris and also insurance - Again will be able to retain the reg number
BobH

Hi Bob, I know for sure that if you want anything at all changed on the Carte Grise then you'll end up with a new-style number.

My chassis number on the H is one digit different from the CG. Luckily the CT testers don't require that to be corrected. I enquired about getting the CT altered by the one digit and was told that the prefecture would automatically issue a new-style number too.

The CT people will probably notice it's the bigger engine in the car and the smaller one on the CG. I'd rather guess that is something that will require a new CG, rather than merely get noted year after year on the proces verbal for the CT, but about that I don't know for sure.