I've traveled fairly extensively around Europe and you do indeed need a credit card in the majority of cases. Some rental agencies will accept a debit card but

I've traveled fairly extensively around Europe and you do indeed need a credit card in the majority of cases. Some rental agencies will accept a debit card but it's risky to just turn up on the assumption that they will. You can find yourself without a car or forced to take up very expensive excess insurance. I've personally had this happen to me more than once and I now travel with a credit card which I have just for car rental purposes. When you book a rental car through an online comparison site, you will almost always see in the small print that bringing a credit card with you is one of the requirements. If you're taking out insurance by default then you may not notice that this is an issue because you're effectively paying to reduce the excess to £0 instead of blocking a deposit on a credit card for them to charge from in the event that you damage the car.