Premium versus Regular Gas

Premium gas is a bit of a mystery to most drivers. Often times we just fill up with regular gas, but see the premium or 'super' options on the pump as well - oftentimes for 20 to 40 cents more per litre. What does that premium gas do? Why would one pay for it? Should I use it in my car? Read on to learn more. 

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What is Premium Gas?

Premium and regular gas are both gasoline from the same source, and both contain the same amount of potential energy - 114,000 BTU's per gallon. Where they differ is in the precise blend of hydrocarbons and other ingredients used to make up the fuel. Fuel is not just pure gasoline. There are other ingredients such as additives (which are used to give a cleaner burn), and bio-ethanol (which is mostly used to increase the octane rating of the fuel). As such, the key difference between regular and premium gasoline is the octane rating. Regular gas is typically rated around 87, whereas premium gas is rated at a 91, or even higher.

Octane Rating: a standard measure of performance of a motor or aviation fuel. The higher the octane rating, the more compression the fuel can handle. Source


Why Would One Pay for Premium Gas?

As mentioned before, premium gas gives a higher octane rating. But why is that desirable? A higher octane rating means that the fuel can handle a higher compression, and as such, burn at a higher temperature. High performance engines sometimes require this higher compression in order to achieve better power and performance. Many sports cars, luxury cars, and roadsters recommend premium fuel in their manuals. 


Should I Use Premium Gas in My Car?

Unless you own a car that specifically recommends premium gas, you should not use it. A vehicle that is designed to run on regular fuel will run best of regular fuel, and premium gas will not only not help with anything, but may in fact reduce performance, since the vehicle is designed to run on a lower octane rating. There are many myths out there about how premium gas increases performance or fuel economy in a standard vehicle (one that doesn't require it), but those are simply myths, with no facts or evidence backing them up. There are however, a lot of other reasons why one might get better mileage on a tank (see our article on improving fuel economy).



Posted on April 25, 2014 .