Yesterday I picked up a good friend at the airport. He will be here for the week on business, so he rented a car. At the rental car facility I noticed a big sign promoting a cheap gas deal: buy your gas in advance at $3.72 per gallon and return the car without filling the tank. The price per gallon at a regular gas station outside the airport is about $3.60 per gallon, so the price of $3.72 doesn't seem that high, right? Wrong. That's the scam.
What the rental car companies don't tell you is that if you buy their gas option they charge you not only for the gas missing from your tank upon return, but for a full tank of gas. Thus, if your rental car has a 15 gallon tank and you return the car with the gas tank 2/3 full, you will still be charged for a full tank: 15 * $3.72 = $55.8, i.e. $11.16 for each of the five gallons of gas you actually used!
Now, $11 per gallon. That's what I call expensive gas.
Of course, you wouldn't know that would be the case unless you specifically asked the car rental agent. In fact, the rental car companies do their best to lead you to believe that you are only paying the "low" $3.72 per gallon. If they really wanted to be fair, they would simply ask you if you wanted to return the car without fueling it for a flat charge of $55 (for example). The language of the offer is carefully chosen to be accurate, but misleading. It has to be, otherwise no one would take this horrible deal.
I am sorry to say that I learned this the hard way several years ago. I returned a rental vehicle only to find an outrageous gas charge was placed on my bill, even though I had returned the car with a virtually full tank of gas. It was a good lesson and I never made the same mistake again.