U-haul has a trick now to get more money out of it's costumers. Instead of giving you a full tank of gas, they give you the truck with a bit more than half, or some variation of the gas tank filled.
As the customer, you then have to guess how much to fill the tank, and because you do not want to pay extra, you are likely to fill it more than they gave you thus giving them more gas then they gave you.
Brilliant scam since if they get even one dollar more in gas from every customer, thats millions more in their pocket. From now on I will not rent a U-Haul unless they give me a full tank of gas - you should do the same.