Odds are low on this happening but not zero. Imagine you pay the AP upfront and have to wait 6 months in the meantime the dealer goes bust.
If you paid by credit card you have section 75 but debit cards and Bacs has zero protection especially after 30 days in the case of debit cards.
I wonder if the garage is trying to dodge giving you section 75 protection by refusing credit cards.
As has been said most BACS happen instantly these days so that’s no excuse. If a dealer pulls that on me I’ll go order elsewhere instead.
Imagine you reject the car on delivery day now you get the hassle of trying to get a refund…