Americans say gas (gasoline) for petrol. Prices are per gallon. 1 US gallon is about 3.8 liters. In almost every state you pump your own gas.
Park so the car's fuel door is next to the pump. A small arrow next to the fuel gauge in your car shows which side it is on.
Turn off the engine. No smoking.
Insert or tap your card at the pump.
The pump may ask for your ZIP code (the 5-digit billing postal code of your card) or "Debit or credit?". If you choose debit, it asks for your PIN.
Choose the grade (see below) by pressing its button.
Open the fuel cap, put the nozzle in and squeeze the handle. It stops by itself when the tank is full.
Hang up the nozzle, close the cap, and take a receipt if you want one.
Many pumps need a US ZIP code. A foreign card has no US ZIP code, so the pump may decline it.
Note your pump number (big number on the pump).
Go inside to the cashier.
Say: "Forty dollars on pump six, please." Pay with card or cash.
Go back and pump. It stops at that amount.
If the tank was full before the amount, go back inside for the change or a refund to your card.
Some stations take cash only inside. Some have a cheaper cash price than the card price; the sign shows both.
Regular: usually 87 octane. Most cars use this.
Mid-grade (plus): usually 89.
Premium: usually 91 to 93. Use it only if your car manual or fuel door says premium.
Diesel: only for diesel cars. Never put diesel in a gasoline car.
Many pumps also show E85, a fuel with much more ethanol, for flex-fuel cars only.
In high mountain areas, octane numbers can be a bit lower.
In a few places an attendant pumps for you. New Jersey is the main state where self-service is not allowed. Stay in the car and tell the attendant the grade and amount ("Regular, fill it up, please").
Air for tires (sometimes costs quarters or a card), a squeegee for windows, toilets, and a small store.
Driving off with the nozzle in the car.
Paying for premium when your car needs regular.
Waiting until the warning light in rural areas, where stations are far apart.