The next time you pull up to the pumps, take a good look at the myriad of options with which a driver is presented. There are octane ratings of 87, 89, 91, and – if you’re at a really good station – an option of 93 octane. Often, the different types of gasoline are advertised as descriptive names with regular and premium being the bookends.

You’d think, then, that premium gasoline would be better for your car, especially given the price hike of the highest grade compared to the cheapest stuff. After all, there has to be some advantage to the more expensive fuel, right?

Not so fast. Those numbers associated with each grade of fuel refer to the octane rating of that particular gasoline. An octane rating is a standard measure of performance for the gasoline we buy every day. The higher the octane number, the more compression the fuel can withstand before igniting in an engine’s cylinder chamber.

In broad terms, gasoline with a bigger octane rating is used in high-performance engines that deploy higher compression ratios to make their gonzo levels of power. The pistons in those engines are squeezing their air/fuel mixture in the cylinder chamber so forcefully that it needs all the help it can get to run properly. A high octane fuel provides that help by furnishing a bigger bang during each piston stroke. Audi recommends using a high octane fuel for its high-strung Audi RS3, for example.

Due to its marketed name, consumers may confuse “premium” gasoline for “better” gasoline. This is not surprising and completely understandable given the dearth of information provided by fuel companies on their products to the average consumer. This is where a lot of common misconceptions arise.

Because the majority of engines are designed to run just fine on 87-octane fuel, putting the expensive stuff in a lower-compression engine will have no effect other than needlessly hoovering money out of your wallet. It won’t make your car run any better or worse, so if you decide to fuel up your car with premium gasoline as a sort of treat, you’re simply giving it a placebo. It won’t run any better, your fuel economy won’t increase and the car won’t be any better off for the experience.

What the latest data tells us.

According to new research carried out by our AAA counterparts in the United States, drivers in that country wasted more than $2.1 billion USD in 12 months by using premium-grade gasoline in vehicles designed to run on regular fuel. In Canada, premium-grades are generally about 10 cents per litre more expensive than their workaday brethren. Assuming a once-a-week fill-up of 75 litres, a motorist could waste nearly $400 a year in needless fuel expense.

“Drivers see the ‘premium’ name at the pump and may assume the fuel is better for their vehicle,” said John Nielsen, AAA’s managing director of Automotive Engineering and Repair. “AAA cautions drivers that premium gasoline is higher octane not higher quality and urges drivers to follow the owner’s manual recommendations for their vehicle’s fuel.”

It’s important to note this is not simply opinion. Our neighbours to the south spent some real time and effort performing field tests to back up their statements. In partnership with a research centre, AAA tested 87-octane (regular) and 93-octane (premium) gasoline in vehicles equipped with a V8, V6 or inline-four engine designed to operate on regular-grade fuel.

To evaluate the effects of using a higher octane fuel when it’s not required by the manufacturer, each vehicle was tested on a dynamometer, which is essentially a treadmill for cars that is designed to measure horsepower and estimate fuel economy. The laboratory testing found no significant increases in any tested category, indicating the practice of using premium gasoline when it’s not required for the vehicle offers no advantage.

“AAA’s tests reveal that there is no benefit to using premium gasoline in a vehicle that requires regular fuel,” said Megan McKernan, who manages the research centre involved in the study. “Premium gasoline is specifically formulated to be compatible with specific types of engine designs and most vehicles cannot take advantage of the higher octane rating.”

The opposite is true, as well. When an engine designed to benefit from premium fuel runs on regular, the immediate translation to the driver can include less responsive acceleration and slightly lower gas mileage. Be sure to pay attention to the manufacturer’s recommendations and feed your car the fuel for which it is designed.

Beware of any gasoline with an octane rating lower of 87, as that stuff is essentially just spicy water. The chances of finding such a poor fuel in Canada is extremely low but keep in mind that countries other than Canada and the U.S. may rate their gasoline on a different scale, so do your homework before heading abroad.

Rather than wasting one’s money on a type of fuel their car doesn’t require, invest those dollars into something that will increase its value at trade-in time. Fixing that noisy front suspension or paying a professional for a complete details job will do a lot more for your car than a tank of “premium” fuel.

For quick reference, we’ve assembled some frequently asked questions below to help answer some common questions about premium fuel and how our American neighbours performed their comparison test.

FAQ's:

What is premium gasoline?

When it comes to gasoline, “premium” refers to the octane rating not the quality of the fuel itself. Higher octane gasoline is formulated to be compatible with specific high-compression engine designs (often found in performance and luxury vehicles) and is less likely to ignite prematurely than regular-grade fuel. This allows those engines to extract more power from the gasoline without suffering from performance issues.

Why did AAA evaluate the effects of using premium gasoline in vehicles designed to operate on regular fuel?

In the last year, AAA’s research shows that 16.5 million Americans ignored manufacturer recommendations for regular gasoline and used premium fuel in their vehicle. These drivers may have the impression that “premium” means “better” and believe they are using a higher-quality gasoline in their vehicle. To understand what, if any, benefit that premium-grade gasoline offers to a vehicle designed to operate on regular-grade gasoline, AAA conducted an independent evaluation of the fuels.

Is there any benefit to using premium gasoline in a vehicle designed to operate on regular fuel?

No. AAA’s testing found no benefit to using premium gasoline in a vehicle that requires regular fuel. The higher octane fuel did not produce more horsepower, result in better fuel economy or produce fewer tailpipe emissions in V6, V8 or inline-four engines. Consumers who drive cars that require regular gas and want to use higher quality fuel should opt for a gasoline that meets TOP TIER standards, which is proven to keep engines 19 times cleaner than non-TOP TIER gasoline.

What brand of gasoline was tested?

To remove variability in fuel quality and additives, certified test fuel with 10% ethanol content was used for all testing. This testing was designed to compare regular-grade (87 octane) and premium-grade (93 octane) gasoline and did not evaluate gasoline additive packages.

How did AAA conduct the testing?

AAA conducted the comprehensive testing in partnership with the Automobile Club of Southern California’s Automotive Research Center in Los Angeles, California. To evaluate the effects of using premium gasoline in a vehicle designed to operate on regular gasoline, each test vehicle was operated on a certified dynamometer.

How did AAA calculate the total annual cost of using premium gasoline when not required by the vehicle manufacturer?

AAA’s proprietary formula includes the number of vehicles that require regular- and premium-grade gasoline, the frequency at which drivers fill their vehicle with premium gasoline when their vehicle requires regular fuel, the total number of licensed U.S. drivers and the per-gallon cost difference between premium and regular gasoline.In Part Two, Matthew delves deeper into the AAA research. Learn more in the blog post, Testing Proves Premium Fuel Benefits Some Vehicles, But at a High Cost.

Our Consumer and Technical Services (CATS) team receives questions about car care, buying a new or used vehicle, auto repairs, vehicle inspection, driving costs and more. If you have a question for CATS, call 1-866-464-6448 or email: cats@caasco.ca