My understanding is that any vehicle that is registered without a genuine customer, and which the dealer intends to sell within 3 months must be declared as a pre-reg. ThIs of course means the car doesn't count towards targets which defeats the object of the registration in the first place.
I have every confidence that all 2,264,737 cars registered last year went straight to an end user, or sat in a storage compound for 90 days - I'm sure none were resold within 3 months, or the manufacturers would have to act....wouldn't they??