What counts as a gas station
Gas bonuses are written against merchants coded as gas stations or service stations. Branded stations such as Shell, Chevron, Exxon and BP generally qualify.
Fuel sold by warehouse clubs usually codes as a gas station too. Fuel sold by a supermarket or a superstore sometimes codes as the store instead, so the gas bonus may not apply.
Electric vehicle charging is its own case. Some issuers count it as gas, some as a separate category, and some as neither. Check the terms before you assume.
Pump and shop are not always the same
Paying at the pump is the cleanest case: the transaction carries the station's fuel code.
Paying inside, or buying snacks in the shop, can go through as a convenience store purchase at some stations. Many cards still pay the gas rate there, but not all.
If a station runs its shop as a separate business, the receipt name often shows it. That is a hint the codes differ.
Caps and the flat-rate test
Gas bonuses commonly run 3% to 5% and often carry a cap, sometimes quarterly. Once the cap is used, the card drops to its base rate.
Compare the gas card against your best flat-rate card at its base rate. A 2% card beats a 1% gas card past its cap every time.
Rotating 5% categories sometimes include gas for one quarter. In that quarter, the rotating card can beat a dedicated gas card, up to its own smaller cap.
