How car/oil industry cheats us of 6 billion dollars a year

Recently, I discovered something that others have known for a while but many don't know. Namely that effectively all modern cars that say they should use Premium (high-octane) gasoline run perfectly fine on regular. Since the early 90s, cars have had more advanced carb/fuel-injector systems which adjust to the octane of the gas and don't knock. Like an idiot, I've been filling my car with premium. The engineers at all the major car vendors have confirmed this.

I worked out that since the USA uses 370 million gallons of gas a day, or 135 billion per year, at 12% premium sales, that's 16 billion gallons of premium sold, almost none of it needed. Call it 15B gallons. At a surcharge of 20 to 30 cents/gallon that's over 3 billion extra dollars charged to no purpose in the USA, and presumably another 3 billion outside (though perhaps they buy less hi-test outside.) The USA uses about 44% of world gasoline.

So why do many cars come with a line in the owner's manual saying to use premium gasoline? Turns out the marketing departments believe customers of higher-end cars are ethralled by horsepower. They want to advertise the highest peak horsepower number they can. And you can deliver a slightly higher peak horsepower on higher octane. Nothing so big that you would notice it outside of extreme driving conditions or pro racing, but you can publish a higher number. So long as you spec the car as using premium.

So to satisfy these marketing numbers, the world is spending about 6 billion extra bucks each year on high octane fuel. And I'm not even considering all the extra infrastructure required (fancier pumps and blending systems, more tanks with risk to leak into the ground etc.)

Many people think high-octane gasoline is "more powerful." In fact, oddly, the octane rating measures how non-explosive the fuel is. The higher the octane, the less likely it will explode under pressure. People think of high-octane fuel as more powerful because with high octane fuel, you can design a higher performance car that works at higher compression, safe in the knowledge you won't get explosions from anything but the spark plug, ie. knocking. The fuel is not higher power, it's the engine, which is why putting premium into a regular car is a waste unless it's knocking. Lead cheaply reduces knocking at low pressure which is why they used to add it until they realized, "holy crap, we're filling our fuel with toxic lead!"

There is still controversy over whether high-compression engines get better mileage than when they run at lower compression with regular.

What a scam. Spread the word.


If your vehicle's engine can burn premium gasoline, you can use that extra horsepower either: 1) to accelerate more quickly to the next red light (a waste), or 2) to cover more miles for each gallon burned.

The data I've seen indicate that the extra cost of premium gas is balanced by the extra mileage gained.

Note that premium gas tends to have a fixed price delta (of 20 to 30 cents/gallon) over regular gas. When regular gas was $1.00/gal a few years back, premium was $1.30. Now that regular is $3.00, premium is $3.30. Same delta in cents/gallon, but as a percentage the price differential for premium has fallen from 30% to 10%.


Can you point me to "the data you've seen" indicating better mileage on premium? Anecodotal tests won't reveal anything Web searches show reports that mileage is the same, slightly worse, or at best a percent or so better based on the theoretical energy density (while the fuel is 6 to 10% more expensive.)

The FTC site, not yet having the guts to tell you that regular is fine for a car whose manual says premium, does report that mileage does not increase. What do you know that they don't?

The data are my own, from a two-year-long experiment. Not scientific, no control, just one driver, one car, similar driving conditions, alternating between tanks of regular and premium. I observed approx 20% improvement in gas mileage running premium versus regular.

If given more horsepower, many/most drivers will use it accelerating harder. No increase in mileage expected there.

But if you drive mildly, you can use that extra horsepower to use less fuel to do the same amount of work....

Let's say you are running your premium-fuel car with regular gas. You accelerate from 0-60 with foot to the floor, using the max power your engine can produce using regular fuel. Acceleration is A.

Now using premium fuel, repeat the 0-60 acceleration. To match the previous acceleration rate A, you won't need to use full throttle (engine is producing more power). That partial throttle setting is using less fuel to do the same amount of work. Therefore better mileage.

To quantify the fuel saved would require digging into the minutiae of the fuel injection system. But an engine that produces more power for a given rate of fuel intake, will do more work.

You are correct that premium and regular gasoline both have almost the same energy density. Premium gas simply resists pre-combustion allowing an engine to compress it more greatly before igniting it, leading to greater efficiency converting fuel to kinetic energy.

Regarding your comment, "And you can deliver a slightly higher peak horsepower on higher octane. Nothing so big that you would notice it outside of extreme driving conditions". I found one source that noted a 10% drop in power output for one particular car when switching from premium to regular. 10% is certainly a noticable difference in everyday driving.


Peak horsepower usually occurs at a level of RPMs that most drivers rarely see. The engineers of the major companies have been quoted as saying most drivers won't notice.

I really, really doubt a 20% mileage increase from 7% more octane.

Using premium gas in an engine designed for it will increase the horsepower throughout the rev range, not just at peak revs.

Don't know where your 7% more octane comment comes from. Engines designed to take premium gas compress the air/gas mixture considerably more than is possible with regular gas, resulting in more mechanical work being done when the charge is ignited. This is unrelated to the difference in energy content of premium versus regular gas. Rather, it's a quirk of internal combustion engine design and the physical properties of vaporized gasoline under high temperature and pressure.

Bottom line is that using regular gas in a car designed (and optimized) for premium gas may or may not save money. It depends on the specific vehicle, the current delta in gas prices (as a percentage), and whether the driver has the discipline to not use the full power available when running premium gas.


If high octane can really result in a significant increase in gas mileage, car manufacturers would design and spec for premium in more of their cars. They are regulated on the combined mileage of their fleet. In order to sell more gas guzzlers they have to sell more high-mileage cars. If they could do that just by moving to premium, I suspect they would -- especially since they could tell the customers, on the sly, that they don't have to buy the more expensive gas.

Of course they care about EPA mileage, not real mileage, and the two are often quite different.

Brad said,
"The FTC site, not yet having the guts to tell you that regular is fine for a car whose manual says premium, does report that mileage does not increase. What do you know that they don’t?"

I don't see where that article reports that mileage doesn't increase when switching between gasoline grades in a car whose manual says to use premium.

It does say that using premium in a car designed only for regular gives no mileage increase. That's a completely different case, and not the subject of your post.


Remember. most americans are stupid.

They buy sports cars because they need that 320HP.. they buy sports utility vehicles becuase some day they might need to go offroading!

The $ isn't wasted.. it's spend on an ego boost.

"I'm so bad ass that I have a car that needs special fuel!"

Perhaps folks fall for the marketing hogwash. Most marketing
slogans are wrong, or at least misleading. Without a strong state
to regulate bullshit, this is something one has to live with in a
free-market economy.

But this is negligible considering the total amount of fuel consumed
in the U.S. Why? Because people drive huge and/or powerful cars
when they don't need to. This leads to much greater waste. Quite
apart from the effects on climate (remember all those folks leaving
New Orleans---in their SUVs?---this of course lowers the true standard
of living. What percentage of the GNP is gas guzzling?

Of course, Bush is a puppet of the oil companies, so don't expect
anything to happen in the States anytime soon.

Does marketing ever serve a useful purpose? If we abolished the entire marketing industry, how much money would get saved? At least education could be improved and scams reduced.

You have no idea what marketing actually is & does in society with a statement like that. Abolish the entire marketing industry? if your under 12 i forgive you, any older and you are really missing what i must be blessed with understanding along with alot of successful people in the world.

will be damaged by using low octane fuel against the mfr instructions. My porsche has lousy knock and performance the one time I ran even 91 octane in it. Your statements are dangerous, aside from being wrong.

There are a few cars that do need premium. Certainly not every BMW though. Didn't look into Porsches. There are cases as well of cars that can run on regular but not as well. However, the research I read indicated that most of the cars that claim a need for premium run just fine, with slightly less top-end power with regular. Some writers claim that no modern car will be hurt by regular any more, their injectors have computers that adjust to elminate pre-ignition (knock), sometimes at a cost in efficiency, but often at no cost.

Check out the web for discussion of your own car on regular. I read quotes from the engineers and Honda and Toyota about their cars.

(Wow, engineers who actually work on engines!)

Let's hear from porsche themselves shall we:

"All Porsche engines are designed for premium, too, but it's not available everywhere. "Our cars must be able to drive all over the world, and so we are able to run on regular," says Jakob Neusser, director of powertrain development at Porsche's research and development center in Weissach, Germany. "You don't have to feel that a mechanical problem or anything else will happen" using regular gas, even in the highest-performance, regular-production Porsches."

So porsche owner, stop with the FUD.

regular has crap in it, whle premium has a lot less of that crap in it.. which equals an overall better fual, burns cleaner too

Most cars that "require" premium fuel also have the intelligence to know when things aren't just as they should be. The ECU will usually account for a lower octane fuel by retarding timing, lowering turbo boost (if so equipped), etc. While the car will still run, and maybe even without any noticable side effects, it is obviously not in its optimal state and you will lose power. You may not even notice the difference in daily driving, but the reality is that it will change the operating environment of your engine to other than factory intended specifications. Over time, running lower octane fuel can lead to (at a minimum) fouled spark plugs and possibly additional wear and tear on engine components. If you don't want to run premium fuel, don't buy a car that recommends it and save yourself the risk of ruining your octane hungry engine.

And the comments at least from Japanese engineers about no harm seem to bear it out. The car is not so much designed for Premium. It simply is able to get more horsepower using Premium, and is designed for that.

By stating the car requires Premium they can advertise the car as being more powerful. And indeed, if going on a trip where such power will be needed -- mountains, towing -- it would be advised to fill with high-octane fuel. For the daily commute, it seems regular would do fine and as the engineers say, the driver will not even notice.

I have been using high octane (super) gas in my fuel injection engine. I just discovered my husband uses regular (low octane) whenever he adds gas to the same vehicle (a 94 Mazda Navajo, 6 cylinder). Is this a problem for the vehicle? I think this is what caused the points to get gummed up in the past which caused the vehicle to "lurch".
Any advice you can provide will be greatly appreciated.

Cars that specify premium gas be used have knock sensors. The knock sensor detects knock caused by running lower octane gas and retards the timing of the spark to prevent detonation. This means that the car can run off regular gas just fine, but it also means in most cases loss of mileage and loss of power. The extent of that loss varies depending on the car, and the condition of the engine (if the engine was already having knocking problems, or the knock sensor was malfunctioning timing may have already been retarded).

Usually the increased cost of premium over regular is offset by the gain in mileage. Plus the gain of power makes it even more worth it.

It is an irrefutable fact that higher octane gas allows an engine to be run with high compression, and high compression engines ARE more efficient, and produce more power for the same amount of fuel burned. This is why auto makers design the engines to run off premium.

More compression does mean more power, but it seems there is doubt about how much more mileage it delivers. As noted, in spite of people's intuitions, high octane means "less likely to explode" (under compression.) If the mileage is indeed better, it would almost suggest we should discourage cars that use low-octane gasoline.

ok ...I just read this , I have an e34 bmw str8 six I have tested using the lowest octane in europe...and the highest ,,,(95-99) octane .I ran 6 tanks of each and consistently found the higher to be about 10 percent better (city driving) long trips were maybe 5 percent (I drove around 700 km on each tank of 70L)..also my engine is alot quiter with the high but I dont' know if 99 octane is overkill for my car,is it causing any damage?,budget wise i think i am better off with the 99 octane but I would like to know if it's bad for my car...thanks.........

High octane means the fuel is **less** naturally explosive, not more. So no, it won't damage your engine to use it, quite the reverse. Your car has to be designed for high octane fuel to get benefit from it, but any car can use it (at no benefit if not designed to get it.)

I understand what this posting is all about and I too would like to know the truth about Regular versus Premium, but here is something we all need to think about. If the prices of gas were not in the $3 range, would we really be worried about more mileage and more power? European said it best: "Of course, Bush is a puppet of the oil companies, so don't expect anything to happen in the States anytime soon." If our government and president really cared about the Gas crisis going on, we would all not be struggling. Welcome to the world of the almighty dollar. Even Bush worships it.

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