If you use a prepaid card or gift card the gas station can deduct up to $100 and hold that amount for a set period of time.
Here's more info- https://www.giftcards.com/gcgf/buy-gas-with-visa
When you swipe your debit or credit card at the pump, the terminal checks to see if your card is valid and if you have enough money (or credit) on your account to complete the purchase–just like it would if you swiped your card at the grocery store. The difference between the two types of transactions, however, is that the grocery store knows exactly how much the total bill will be and places a hold of that amount on your account until the transaction is settled. If your bill is $43.51, for example, the hold (called a “pre-authorization charge”) will also be for $43.51.
At the gas pump, however, the system does not know how much it will cost to fill up your tank, so it makes a guess. A typical pre-authorization charge at a gas pump is about $75. If your gift card has a balance that is less than the pre-authorization charge, the gift card will be declined.