register on a '15 plate or wait for '65?

[Fulmentaljack3t]

So I ordered an M5 a couple of weeks ago and was expecting around a 14 week wait hence it would be on the new '65 plate. However the car is apparently now built and deliver will be around 20th July.
So the question is do I register it when it arrives and get it on '15 plate or store it at the dealers until September and register it on the new '65? The dealer reckons it won't make a difference to value in the future as the value it on the build month not the plate and the plan will be to exchange it for a new M5 when it's released.

[Fulmentaljack3t]

Thanks, there is a guaranteed future value. Of course I hope there will be more equity in the car to put towards another when i come to swap it in. Yes it will go back to the dealer. Perhaps the only upside to the newer plate is the snobbery factor!