Originally Posted by
Palal
Ideally you want a Full>Full. Some force a Full>Empty policy on you.
To elaborate, several of the cheap companies - most notably Goldcar - make you pay upfront at the counter for a full tank of fuel, plus an admin fee of 20/25 euros or so. They then refund what you have left, but keep the fee. So in effect your rental cost is the amount you pay online plus the compulsory fee. This can make quite a big difference to what appear at the outset to be very cheap rentals.
Note with Goldcar, if you book direct via their website you can pay a little extra for full/full, i.e. you avoid having to buy the fuel upfront. I generally prefer to do this.
Also watch out for any diesel 'supplements' being applied, even if you didn't book a diesel but are 'upgraded' to one!