That statement in one form or another has been part of car rentals since the beginning. In the early days, it was Cheap car rental Waikiki a straight out principle issue. You used it, you replace it. At some point between then, and now, someone realized that “there’s a lot of money to be made with the gas tank on rentals.
For those who don’t know, lets explain your refuelling options in car rentals. When you rent a car, the car usually comes with a full tank of gas. In some circumstances, it comes with a partially full tank. In either case, the rental company will give you three options. Bring it back at the same level you got it at, (full) prepay for a full tank of gas (GSO) and bring it back empty, or bring it back empty and pay a refuelling charge (FSO) of a more expensive per gallon rate.
Fuel Service Option (FSO) is almost always the costliest option. Up and down the California Coast, most cities have FSO charges around $5.99 a gallon (and with recent prices, even higher). Around the country, its not much better. While your mileage may vary on the actual price per gallon, the FSO charges are almost always a good Dollar per gallon more expensive than the prevailing GSO (prepaid) rate or the rate of the local gas stations. It may seem that there is no really good reason to use the FSO, but there is. While most FSO users are people with more money than time or people who forgot to fill up the gas tank, there is one segment where it is cheaper to use this service than any other.
If you have a discount code, it may be because of your employer. Some employers, such as Microsoft and Government Contracts like Lockheed Martin have negotiated rates where the same dollar amount for fuel refueling is charged nationwide. Depending on the market, it may not be that bad. In one circumstance, a friend of mine who worked for one of the above mentioned companies went on a trip to Kona, Hawaii. On that trip, the fuel service option refueling price was less than the per gallon prices of all the local gas stations within 5 miles of the airport. In that case, its always best to just bring the car back as it is.
On the other end of the spectrum, the GSO option is a prepaid full tank of gas at a specific rate. In most car rental agencies, the GSO price is the average of the three closest gas stations. With this average, the multiply the tank capacity by that number and offer it as a flat rate to fill up the tank. But let the buyer beware. If the tank is not totally empty when you return it, you do not get a refund on the gas you use. You have effectively paid for a full tank of gas and if your not “empty” on return, you’ve just given the car rental agency free gas to use.