EconomyCarRentals

Definitely the cheapest I could find.

On collecting car Sixt made charge for 253 against card for CDW, when "pay at airport charge" was 116 . Sixt employee said it would be returned on drop-off if car was not damaged, after six hours doubt crept in, in the event unnecessary worry, that is how it worked.
Then got the final invoice from Sixt it was for 133, they had invented charge for checking petrol tank which was full. I alerted Car Rentals and after 6 hours contacted Sixt by e-mail they responded immediately and returned 133 and re-invoiced 116. All very efficient .
Will definitely use car rentals again with more trust and see if unnecessary charges re-occur. I suppose you are taking a gamble that Car Rentals will cover the CDW in the event of a crash otherwise the company will come after you.