Premium or Regular Gas? How to Choose at the Pump

You might not need to purchase premium gas. Learn more about the gas your vehicle needs.

If you’re like many drivers, the choice you make at the gas station is simple, and you buy regular, unleaded gasoline. 

But have you ever wondered what the difference is between each octane and why some drivers spend more to fill up their cars with premium gas?

Gasoline, explained: What do gas octane levels mean?

Most gas stations in the U.S. offer three octane levels: regular (about 87), mid-grade (about 89), and premium (91 to 93). The octane level measures the gasoline’s compression. 

Vehicles with high-compression engines like sports cars or foreign cars might require gas with higher octane levels than other vehicles to prevent engine knocking.

What is the difference between premium gas and regular gas?

Regular unleaded gas is typically the cheapest gas per gallon, as it is the most commonly used octane. Better quality ingredients and advances in technology make regular gas the best and most affordable option for most drivers.

Premium gas, as the name suggests, is the most expensive octane at the gas station. Some luxury car manufacturers recommend premium gas. 

Not using premium gas when recommended can cause engine knocking, which can eventually decrease the engine’s efficiency. 

Double-check whether your car’s manufacturer requires premium or recommends premium gas so you can get the expected vehicle performance.

Should I buy mid-grade gas?

Few car manufacturers suggest mid-grade gas. As the name would suggest, this octane offers a middle ground. It has slightly more additives than regular gas, but generally, the results won’t be noticeable.

What kind of gas should I get for my vehicle?

Your car owner’s manual will list the recommended gas for your exact vehicle. If your car is designed to run on regular gas, you won’t necessarily get any additional performance or benefits if you fill up with premium. 

It is a myth that splurging or getting more premium gas will allow your vehicle to run faster or get better gas mileage if it just needs regular gas.

Can I use diesel for my car?

Diesel fuel has an octane rating of 25 to 30, much lower than even regular gas. It isn’t a good idea to fill up your vehicle with diesel unless recommended by your car manufacturer.

Because of the lower octane rating, diesel can cause damage to your vehicle’s engine, so don’t choose diesel if it has a lower price tag at the gas station. You will pay for the difference and more with potential car repairs.

Is the type of gas you use important to your car’s health?

It’s important to follow your car manufacturer’s recommendations to get the most from your vehicle.

When filling up at the gas station, you might see three options: Regular, mid-grade, and premium. If your car manual calls for premium or mid-grade gas, but you pump regular gas instead, the lower octane level could damage your vehicle’s engine, reduce engine power, and lower your fuel economy.

By contrast, some over-achieving drivers whose cars only call for regular gas but add premium gas may not hurt your engine, but it probably won’t do much besides waste your money.

How does regular car maintenance keep your vehicle in good health?

If you’re curious about how the type of gas you use affects your car’s health, you might be looking for other ways to keep your vehicle in good condition.

One way to keep your car running strong is by driving less often.

Low-mileage drivers put less strain on their vehicles and generally need to get their vehicle maintained less frequently than road warriors or people who drive more often.

If you don’t find yourself at the gas pump very often, you also might want to consider switching to pay-how-you-drive auto insurance

At Metromile, our pay-per-mile insurance policies focus on the miles you drive. So low-mileage drivers can save a lot of money. Driving less could be a great way to help offset the cost of fuel, especially if your car requires premium gasoline!

The table below shows the average annual car insurance savings enjoyed by new Metromile customers:

Miles Driven Per YearPer MonthPer WeekSavings*
10,000 miles833 miles192 miles$541
6,000 miles500 miles115 miles$741
2,500 miles208 miles48 miles$947
* Average annual car insurance savings by new customers surveyed who saved with Metromile in 2018.

The bottom line

Looking for ways to save money on gas without skimping on the health of your vehicle?

Whether your car takes regular or premium gas, low-mileage drivers can save money on gas by filling up at the tank less often. And as you’ve seen, you could also save hundreds of dollars on car insurance.

If you think you might be a low-mileage driver, get a free quote from Metromile. You can even try pay-per-mile auto insurance before you buy with Ride Along™, a free app feature (not insurance coverage, you’ll need to keep your current provider’s policy to maintain insurance) that lets you see how much you could save from your actual driving.