This of course is understandable as it is going to take time taking the car to a petrol filling station, even if it is only a hundred metres away from their car hire depot.
If the car has been returned full it can be efficiently checked over, cleaned and be ready for the next customer and with shortages of car hire vehicles in July and August 2009 in many parts of Europe this has been most important.
There are a few car hire companies that actually encourage a renter to return the car empty, so they can automatically charge the customer an administration fee.
So always check the situation out when you are signing up the car hire documentation at the check in desk and then you can save money.
When you do fill up with petrol or diesel, remember to keep the receipt so you can show it to the car hire return check in staff if asked. There have been cases whereby renters have added water to make the tank full, or bought diesel instead of unleaded petrol. The majority of rental vehicles have stickers on the outside of the fuel cap area and inside the area as well.
Another way to save money when renting a hire car is to buy your car hire excess insurance from a specialist insurance provider. Their daily policies are normally a lot cheaper than those provided as an additional cost onto the car rental by the car hire company. The reason is fairly straightforward they add a higher profit margin on. The website http://www.insurance4carrental.com/ acts as an introducer advertising service for a couple of providers and you can buy daily car hire excess policies or an even better idea is the annual policy.