Difference Between Regular Unleaded and Premium Gas

Updated on June 28, 2017

Having to choose between regular unleaded and premium gas for your vehicle is not a rare occurrence. There’s always the substantial price difference to think about, but is it worth the gamble to use cheaper gas on your vehicle?


Regular Unleaded

Regular unleaded gas, or RUG, is the most familiar type of gasoline for most motorists. It is a highly flammable crude oil byproduct that does not contain any lead compounds. This means regular unleaded gas is more eco-friendly and poses less of a health hazard compared to leaded gas. Studies have shown that lead in gas can cause cancer and stunted growth among children. Lead has also been proven to cause cancer.

Regular unleaded gas has an octane rating of 87. In most cases, gas octane ratings describe how the gas mixture can efficiently withstand knocking or pre-ignition. The low octane rating makes regular unleaded gas less expensive compared to other types of fuel mixtures. While prices vary depending on the region, the average range is 20 to 40 cents less per gallon. This amount can run up to hundreds of dollars in savings annually, especially if the individual drives frequently.

Regular unleaded gas requires a small amount of time to burn. This makes it favorable for low compression engines that do not require a lot of power.

Premium gas

Premium gas is a highly combustible engine fuel derived from crude oil. It is characterized by a few variants, and the typical octane rating of premium gasoline is 90 to 94. This is the reason premium gas is also referred to as high-octane gas. More importantly, a higher octane rating normally means higher engine resistance to knocking. High-octane gas burns slowly, a feature ideal for high-performance vehicles which produce a lot of power. Premium gas normally costs 20 to 40 cents higher per gallon compared to other fuel variants.

Regular Unleaded vs Premium Gas

So what’s the difference between regular unleaded and premium gas? Although both types of engine fuel are byproducts of crude oil, regular unleaded gas works differently than premium gas.

Regular unleaded gas is a highly combustible engine fuel that is derived from crude oil that has a typical octane rating of 87. While premium gasoline is also a byproduct of crude oil, it has an octane rating that is typically at 90 to 94. A high octane rating allows better fuel efficiency and resistance to engine knock which can damage engine parts over time. Fuel prices differ by region, but regular unleaded gas is cheaper than premium gas – typically 20 to 40 cents cheaper.

Regular unleaded gas burns more quickly than premium gasoline. This makes the former well suited for lower performance engines. In contrast, high-performance engines require slow burning premium gas to produce a great amount of power.

While regular unleaded gas seems to be a lesser choice, newer engines are equipped with circuit boards that allow them to perform at par with high-performance engines. Experts suggest that you always check the vehicle’s manual to find out which is the most suited type of unleaded gasoline to use.

Comparison Chart

Regular Unleaded GasPremium Gas
Has an octane rating of 87Has an octane rating of 91 to 94
Suitable for low-performance enginesSuitable for high-performance engines


Here’s a video about premium and regular gasoline tested on five vehicles.