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Premium vs. regular gas mileage

Will using regular gasoline in a 2006 Mini Cooper non-S hurt the engine?

It shouldn’t hurt, if by that you mean do irreversible mechanical damamge. But if it specifies premium that’s what you should use unless it’s not available. Why do you ask?

We like the Mini but don’t want to pay extra for premium. If it reduces the mileage by 2-3 mph, we can live with that as long as it doesn’t hurt the engine.

We need to know what the manufacture says.  Check the owner's manual or look for a sticker on the car that defines the fuel type.  
  • Requires High Octane: Then you use nothing but high octane!
  • Recommends High Octane: You may use regular or high octane. However you will likely have less power and lower fuel mileage using regular.
  • Does not recommend or require high test, then use regular. Using high test will not gain a thing, no more power or life.

The manufacturer says “premium fuel required.”

That means you need to use premium fuel.

Yep, “required” is self explanatory.

Trying to save money on fuel costs by using regular in an engine that is designed to run on premium is a fallacy. It won’t blow up your engine, but 100,000 miles from now there may be more wear and tear.

If the car specifies premium, then I’d use it, for the long term benefit of the engine. Using regular just doesn’t pan out, any way you look at it.

Let’s say for arument’s sake you drive 1200 miles a month, with an average fuel economy of 20mpg with premium. That’s 60 gallons a month. Today, premium is 3.699/gallon. $221.94 per month. Regular is 3.499/galllon. $209.94 per month. You’ll save $12 a month. Who cares?

Now, if you lose just one mile per gallon using regular, you’ll use 63 gallons in a month, costing you $220.79 per month, versus #221.94 on premium. A dollar a month? Really.

Cars are equipped with knock sensors. If the engine is knocking because you’re using regular instead of hi-test the ECU will retard the timing which will mean lower performance and worse gas mileage. That’s the BEST case scenario.

The WORSE case scenario…is the knock sensor fails and the engine is knocking and blows a hole in one or more of the pistons costing you THOUSANDS of dollars.

How much money you going to save by using regular of high-test???

I don’t know offhand if your particular car requires or recommends premium, but I have to comment on your statement about losing 2 to 3 MPG. If you actually lose that much, you’re very likely not to come out ahead at all. Have you actually done the math here? Does it make sense to give up performance and possibly risk engine damage for essentially no gain?

If you don’t want to pay extra for premium, why did you buy a Mini? There are lots of cars out there that don’t require it.


The car has what, a 10 gallon tank? With 20 cents being the average price difference, you’re not even gonna save 2 bucks each time you fill up using regular.

Wow. I have NEVER seen an engine blow a hole due to low octane. The knock is not due to high explosive but due to pre detonation. At the very most this causes premature valve wear. NOT hole in the engine.

Need More???

My 1980 Ford Bronco 351M.
Could hear pinging during acceleration yet chose to continue low octane gas for atleast a year ( of pinging ).
Blew the top off of one piston, a hole clean through the entire piston head top.
One ten dollar used piston and ‘on the road again’.
Although not listed to need high octane, it told me otherwise by its performance ( carburated, high altitude, old used truck )

1992 Ford Explorer did not ‘require’ premium fuel.
Yet I would consistantly see 60 miles more per tank.

I once advanced the timing too far on my 1971 Maverick before I started on a highway trip. I had changed the distributor points and the spark plugs. Out on the highway, when I would accelerate even moderately, the engine would ping. At my first gasoline stop, I put in premium fuel. The pinging stopped and the miles per gallon really increased. I debated as to whether to leave the timing advanced and use premium, or retard the spark and use regular. I finally retarded the ignition a couple of degrees, but missed the better performance and the higher mpg.
With a 2006 Mini Cooper, if the manual calls for premium, I would use premium.

Initially, no, it wouldn’t hurt the engine.
But over time, it possibly can.

How many miles would that take?
I don’t think anyone here knows the answer to that question.
But it is possible that it can cause damage.


You will save $74 for each 10,000 miles you drive. You should reconsider the idea of using regular gas in your Mini. That’s $1.42 per week. You’ll never miss the money.