Well, I wasn't going to make a scene of it, but as Europa Goldcar do not wish to respond to any of my questions regarding a €10 charge for an extra that was not requested by me, I feel I have to warn others.
I recently booked a Clio size car from Murcia airport. Our flight was delayed, so everyone was in a hurry; passengers to be on their way and car hire clerks to be going home. As a returning customer, all of my paperwork had been pre- filled, so I just had to sign the credit card paperwork and the contract. The car had been upgraded to a Fiat Brava diesel. It wasn't until the following morning when reading through the paperwork that I noticed I had been charged the 10€ fee for a diesel, even though I had not requested a diesel vehicle. I know I should have checked at the time of signing, but as I said previously, it was a rush to get done, by everyone.
Several emails later to various addresses within the agency have drawn a blank. It may only have been a small sum, but that small sum multiplied by (potentially) many, added to the full/ empty rip off has got my blood boiling 
.
I used them this time as I had previously had a great experience with them, but I won't be using them again.
Mark