A quick warning for anyone doing 'mileage run'-type rentals - if you do under a certain mileage (apologies I can't remember the exact figure) you might be given a fuel charge regardless. Presumably on the assumption that it wouldn't show up on the gauge clearly. If you rent a car for a day to achieve status and only do a few miles, make sure you top off the fuel, take your receipt in and ensure you don't get charged.