The things I do for this blog in the name of personal finance.
One day last month I got into a lunchtime conversation at work with a contractor who tried to convince me he had good reasons for putting premium gasoline in his Toyota Corolla, the biggest of which was that he got better gas mileage. I found that a bit hard to believe – but more on that in a second.
For the record, Consumer Reports notes that using premium gas in an engine that is designed to run on regular does not improve performance.
Unlike my contractor friend, I think most people understand that premium gasoline is generally meant for use by high performance cars and the occasional Sherman tank. Even so, premium gasoline sales are not insignificant, with market share consistently higher than 10%.
I don’t know about you but, regardless of how you calculate fuel economy, 10% of the cars I see on the road aren’t high performance vehicles — or Sherman tanks for that matter — so anecdotal evidence suggests a lot of people still believe in the magical powers of premium gasoline.
In fact, the magical power that allows premium gasoline to turn a Toyota Corolla into a 540-hp Shelby GT500 is eerily similar to the claims of those male enhancement drugs that promise to turn us average Joes into superhuman love machines that would make even the late great Barry White envious. I mean, just look at the evidence:
But I digress. Let’s go back to the contractor who swears he gets better gas mileage. In addition to prolonging the life of his engine, this guy insists that premium gasoline gives him an extra three miles per gallon too. Assuming he gets 40 miles per gallon, that would result in an improvement of only 7.5%, which is very close to the mark-up for premium gas anyway. Fine.
So just for grins I performed my own month-long experiment using only premium gasoline in my trusty 1997 Honda Civic. I already had plenty of gas mileage data using regular gas from an earlier commuter analysis I conducted; it found that I was averaging 40 mpg with regular gasoline.
As for my results using premium fuel? Well, over a 30-day period I averaged one mpg less using the premium gasoline — and I paid an additional $6.44 for the privilege.
Talk about feeling like a chump. I’ll bet a lot of suckers people who bought those magic pills felt the same way after they finally, er, measured their results too.
The lesson, of course, is that you shouldn’t buy into the hype of thinking that just because something costs more it has to be better. Premium gasoline is intended for use on a relatively narrow niche of cars — so if you aren’t sure what type of fuel your car should be using, check your owner’s manual.
The odds are the manufacturer probably recommends good ol’ regular 87 octane gasoline.
Photo Credit: dno1967b
Len,
I’m no expert on gasoline. But, here is the reason for premium gas. It’s higher octane rating menas that it has a higher detonation level. It is designed for performance cars that have higher compression. Regular fuel may pre-detonate or “ping” in a performance car, which can damage the engine. Premium has no extra benefit in a car with lower compression, besides possibly some cleaning additives.
It is my understanding that premium fuel actually has fewer BTUs per gallon than regular, so it should yield lower mileage. (Which was verified by your testing.) Diesel fuel has even lower octane and higher BTUs per gallon than gas, which is why diesel engines get better mileage and terrorists use it in fertalizer bombs.
Gasoline is actually a collection of a bunch of different hydrocarbons. Short chain (fewer carbon atoms molecules) vaporize more quickly and at lower temperatures. “Regular” gas, and winter blends have more of these, and less of the more stable longer chain molecules. “Octane” is actually an eight carbon molecule used to benchmark the result of a batch from the refinery.
I’m not too sure about actual BTU content. The key feature of premium is that it will not ignite at higher cylinder pressures until the spark occurs. So, no knock or ping which causes a loss of power and may actually result in engine management changes in modern computer controlled engines.
An older car may benefit from higher octane gas if it has carbon built up on valves and the pistons. This serves to increase the compression ratio to make it functionally more like a performance type engine. That is how it may be possible to get better mileage when using higher grades of gasoline.
You certainly can’t be accused of misleading advertising… your blog really is off-beat. And I don’t mean that in a bad way! So can I assume the mid-grade gas is also a waste?
entertaining as always.
in regards to mid grade, a friends dad always uses the mid grade but he found out about the mixing at the pump and now mixes his own. He pumps 50% regular amd 50% premium giving a blend all his own.
maybe your next test should involve those male *ahem* enhancers. Sorry I won’t be available to be part of the panel however LOL
Awesome story. I’m still sad that my Audi requires premium, but now I can really make fun of my friends whose cars dont need it.
I asked so many experts. Everyone of them said whatever the manufacture says to use, you just use that. If the car is made for regular unleaded, don’t use anything else. If you use different grade than the manufacturer’s, more carbon gets deposited in the combustion chambers and that ain’t good.
Check your manufacturer’s manual and use exactly the same grade as the book says.
My car (Mini Cooper) and both of my motorcycles (Harley and an Aprilia) all take Premium, as specified in the owners manuals.
What I find just as interesting as your findings here is that the term “premium” varies by state! In California, the different octane ratings are different than in Utah, so the lowest octane for Cali, 87, is higher than the lowest octane rating for Utah, 85. There is no standardization here!
In your case, it is a function of altitude. Cars work well at higher altitudes with lower octane gas. And, you save some money. It all has to do with pressurization of the air/fuel mixture in the engine’s cylinders and the resulting burn character.
I get 50mpg from my civic coupe of the same year, manual, never using ac, running bp 98 octane premium fuel
LOL- great post. i couldn’t agree more why do people not just conduct there own research. its like if you tell someone that it works they automatically think it works. now i understand the power of word of mouth marketing but come on. premium gas, what a rip off.
People think they’re getting something better because they’re paying more. They’ll pay the higher price and tell themselves they’re doing better by it, facts be damned.
It’s not until you’ve been burned a bunch of times by hype that you begin to recognize an upsell. In the meantime, you go about happily paying more, thinking more gets you the better stuff. Sometimes maybe, but nowhere near all the time.
Heck, look at all the people who drink bottled water? I’m a dope working for a living when I’d be relaxing on a beach in the tropics if I’d hadn’t been too common to realize that a whole lot of people would pay a premium for something they could get for free, just by putting it in a bottle and calling it “Le Water”.
Yep, I do the regular gasoline. I don’t buy the hype on the premium stuff. I’ve had plenty of people who know cars and have told me to just stick w/ the regular!
This analogy absolutely made my day. I see why your blog was voted as one of the best. I remember years ago when my husband drove either a Cadillac or a Lincoln. Both absolutely needed the high performance gasoline. Then I purchased a smaller car and so as not to feel bad about not using the high performance, I switched down to mid-grade and then occasionally felt like I needed to mix the two. Considering the regular as an option didn’t dawn on me. The light bulb finally went off and for years I have used only the regular without any adverse reactions. With gas prices continuing to escalate, even switching to mid-grade is not a considered alternative.
I love Consumer Reports. It’s a magazine I like to check out before making large purchases. I’ve never paid for premium gas, my Honda doesn’t need it. Good to know I haven’t been wasting my money!
Len,
What if your car (Saab 9-3) recommends AON 90 for ‘optimum performance’? Think I should mix the 89 and the 91 that California offers, or be lazy and stick with the 91?
Or should I let the knock sensors in my car scale down the boost and just get 87? Haha, decisions, decisions!
I’ll assume those were rhetorical questions, Paul.
(But your point is well-taken.)
Finally one person mentioned knock sensors.
In older cars, the state of tune was set, and if your car knocked, you had to use a higher octane. I had an old Toyota that had a small dial on the distributor cap that allowed you to make fine adjustments to the timing. That way, you could use whatever gas was available, and adjust for no knock.
I have done a fair amount of testing in this area, with both motorcycles and cars. Trying to stay with the same gas station, and similar driving. My experiences show that each vehicle varies in mileage with different grades, some more than others. For example, my car gets it’s best MPG on regular. One bike gets it’s best mileage on premium, and one bike gets it’s best on mid grade. I have kept lots of records over the years, and looking at them shows similar conditions with other vehicles.
That being said, in NO case did the increased mileage justify the increased cost. So, it still stands that the only good reason to use premium is if your vehicle knocks with regular or midgrade.
I use regular in the car and one bike, but vary the grade on the other bike based on typical temps. It will ping with mid-grade if it is VERY hot, and will ping with low test unless the temps are fairly cool. So, Hitest in the summer, low test in the winter and mid to low in the fall and spring.
There is another wrinkle to this story…and that is ethanol….. and where you live determines how much ethanol is in your fuel. This alcohol additive bonds with water. Over time the water is released from solution and settles to the bottom of your fuel tank….and depending on your fuel pump design it may or may not enter your entire fuel system. This isn’t a problem if you drive often, but if you don’t? Here is a concrete example. I have a restored 81 VW Westfalia now worth at least $30K US dollars. My wife and I use it for local camping trips and when we visit relatives. It has an inline fuel pump and one day it started to make noise as it began to cavitate. (Buzzing noise). I changed out the fuel filter and drained the lines for a while. Water in the fuel. Put everything back together and within 5 minutes had to do it again. This involves putting the machine on a ramp, leveling it, then removing the skid pan and offending parts. Water eats and destroys high pressure fuel pumps and they are worth $300 plus the hassle of the swap so you either pay me now or pay me later kind of thing. To make a long story short I finally had to drain and filter the tank and flush the tank with filtered fuel several times to remove all the water from the fuel system. I then switched to high test which in Canada contains NO ETHANOL. Problem solved. My work truck is only 20 years old and doesn’t seem to have this problem, but then again it doesn’t have an inline fuel pump. For all I know the tank could have 2″ of water in the bottom.
I maintain our vehicles and have no wish to replace them with today’s complicated computers on wheels otherwise known as financial black holes.
Ethanol? Minnesota wants to increase levels to 15%. Hard to stomach as the energy required to grow the corn and make the ethanol consumes more energy than what the ethanol is supposed to be substituting. God knows what California mandates.
Regards
You’re absolutely right that putting high octane gas in a car that is designed for low octane gas is completely wasteful, but you don’t have to have a 500+ HP monster to drive a car designed for premium grade fuel. Many 2-300 HP cars are tuned for 91+ octane.
Any recent car that is designed for high octane will have a knock sensor and can safely run on lower octane gas, however if the knock sensor kicks in, you will lose efficiency. Driving a car designed for high octane fuel on 87 octane will result in lower mpg. On the flipside, as you discovered, running a car desinged for 87 octane on high octane fuel will just drain your wallet faster.
Point is, read your manual. Use the minimum octane that the station offers that is >= what the manufacturer recommends.
Never thought of comparing gas to well say male enhancement drugs but I guess it works. I hate to say most of the cars I have been driving requires high octane. Though I dont think it should make a difference I have notice how my cars act when I didnt put the require octane in the tank.
It’s better to know what your car needs and are compatible with. I think a bit of research is needed to do this so that you don’t have to spend on premium gas, which costs higher compared with other, and you will save thousands of money in the long run.
Very apt comparison! Premium gas one reason I try to stay away from the allure of luxury cars. There’s also higher insurance and maintenance costs. Not to mention paying $10,000 extra for a car because of its name. I have much better uses for my money.
I personally found better mileage on premium fuel, so that’s why I stick to it. Also, my car has a check engine light on for the knock sensor, so I definitely want to give it as much help as I can.
LOL
Len, thank you. I really needed a dose of your insanity this morning. I have been laughing for 10 minutes.
I really hated having to give up being a chemical engineer. They are in a world all their own.
I shall refrain from making jokes about enhancement pills. (Only because this site is mixed company).
Anytime, Bill! 😄 Glad you enjoyed the article.
So many have performed their own gas tests. In a similar vein has anyone performed their own ED drug test? Maybe the ED claims are true??? 😲
Since selecting this article my feed is now full of ED ads. The algorithm is in full swing.
Oops. Sorry about that, Frank! 😬