Basically retail futures trading. But what happens when price raises suddenly and they run out of funds. Do they reveal what their capitalization is? If it is at least a Billion $, you can say they are stable; otherwise, be prepared to lose your money when they go under. But if you only buy $100 at a time, no big deal.
I think Costco is a better deal. For same membership fee, you save on gas and other stuff.
If you really believe gas price is going up, buy some futures position.
