But if you use car finance doesn't this cover you with section 75 ? Or can you use your card and say pay £500 or £1000, if there is any problem ie catastrophic turbo failure , garage won't sort it. You have protection ? But you have only paid £250 on the card ? What is it protecting against if you have only put the £250 on the card ?.
Just putting £100 on a credit card or other form of credit gives you full protection if something goes wrong with the purchased item and the seller is unreasonable, or if for example the retailer goes bust between you paying and taking possesion of the item.
IIRC there is an upper limit (25k or something?) if it's a part payment but basically if the garage tried to get out of their legally mandated warranty or something the credit company (be it card or finance) can basically fight for you or refund what you've paid.
I never pay for anything that isn't going to be walking out the door with me, or that is high value without using the credit card for at least part of the purchase.
When one of the carpet places went bust years ago my parents had paid for carpet, fixings, delivery and fitting, the company tried to get my parents to accept just the carpet and collect it with no refund for the other goods and services they'd paid for, the credit card basically said "yeah that's not on, fill this form in and we'll cancel the payment. For now it's not counting towards your credit limit or payments".