There’s a couple of things to think about.
It’s possible to buy a VAT qualifying used car. Ex demonstrators or cars owned by leasing or hire companies can be VAT qualifying. The purchase price might be £12,000, your invoice will actually show £10,000 + £2,000 VAT.
Margin rated cars are explained above – previous owner wasn’t able to claim the VAT back so the dealer pays VAT on their profit.
It’s all irrelevant anyway as unless you’re a taxi firm, a leasing company or a hire company then you can’t claim the VAT back on a car even if you’re VAT registered. You want a nice van for that.