I don't know what 'payment terms' VW operate under. Is it 30 days, 3 months? I think it might be 30 days. Check their payment terms.
If invoiced now, and if the invoice has to be settled in 30 days, then you should avoid 20% VAT if payment is made within this time period.
You may then register and collect the car when you so wish, dealer being agreeable.
Tricky.
Nothing is certain but Death and Taxes.
Where's RED? He's the accountant.