Legal Question in Consumer Law in New Jersey

Re: Gas Station

You're probably not amused, but your question does have some entertaining aspects.

To illustrate the law, let's take it out of the context of gasoline and suppose, for example, that you ordered five boxes of paper and the supplier delivered ten. You have to pay for the five that you ordered. You also have to notify the supplier and to make reasonable efforts to keep the other five boxes safe for a reasonable time pending return instructions from the supplier at the supplier's expense. (There is an exception for unsolicited merchandise received through the U.S. Mail which may usually be treated as a gift.)

A unilateral mistake does not create a contract of sale. Therefore, you have no contractual obligation to pay for the gasoline. However, if you use it, you may be obligated to pay the fair market value for it. That may not necessarily be the sale price.

All of that is kind of academic because it doesn't work very well in the case of retail gasoline sales. However, there is no requirement for you to hang around at the station. The error is the vendor's and your obligation is to cooperate in correcting it in a reasonable manner.