You may technically be correct, as the UK is no longer in the EU. You can buy cars with a debit card in the UK, haven't tried using a credit card.

Debit card works fine to buy a car all over Europe and generally everyone here has a debit card. Creditcard usually doesn't work due to the much higher fees (2 to 3% for credit vs 0.2% for debit).

Is it possible to buy with cash?

Not sure about other countries, but in Spain you can't pay anything above three thousand euros (IIRC) in cash.

People downvoting others in disbelief should try to find a source by themselves before.

2500 EUR if you live in Spain

https://www.agenciatributaria.es/AEAT.internet/Inicio/_Segme...

It's probably not possible in most of EU because there is a limit for cash transaction which is I think 15 000 Euro (not sure if EU wide, but definitely here in Slovakia), over that you need to do a bank-wire transfer. All new cars are paid this way - or you purchase it with a loan / lease and don't need to put down this amount of money at once. Most new car dealers don't even have a cash register and would not take such an amount of money from you in cash. This is due to prevent money-laundering.

Depends on the country and the amount of cash [0]

[0] https://www.europe-consommateurs.eu/fileadmin/user_upload/eu...