A question I ran across last week at The Farm Press of all places that asked the following, reprinted from Consumer Reports.
>Two cars drive into a service station: a brand new Corvette with a 400-hp V8 engine that’ll go 0-60 mph in a breathtaking 4.3 seconds; the other a new Mini Cooper convertible with a 4-cylinder, 115-hp engine that does 0-60 in a ho-hum 7.1 seconds.
>The $3-plus per gallon question: Which one pulls up to the premium fuel tank?
Of course we all know the answer to the question.
They go on.
>Nonetheless, one wonders: If GM can wring blazing performance out of its 400-hp ‘Vette burning regular gas, why does a smaller, less powerful Mazda Miata specify premium? And if a hulking, weighty 403-hp V8 Cadillac Escalade SUV can run OK on regular gas, why should an equally bulky, heavy 216-hp V6 Land Rover SUV’s specs call for premium?
I have actually tested this in my MINI with both regular unleaded and mid-grade. I have also heard of some R53 owners that have run regular unleaded without any serious performance problems. Not so in an R50 Cooper. On regular (87 octane) unleaded gas, my MINI barely had enough power to enter a highway at the posted limit and going uphill was quite a challenge. And if you ever wondered what it sounds like when a MINI knocks and pings, this is the best way to do it.
So, why do we need to run premium fuel in our cars? Compression ratio. It takes quite a bit of power to move the piston up and down in the cylinder in the most efficient and productive way. The only way to get that power is by using premium fuel.
In most markets, the price difference is about US$.20 per gallon. On a 10 gallon fill-up, that’s a difference of US$2.00. For most of you, that’s about US$4.00 per month or less.
Trust me on this one, skip a latte and put the good stuff in the tank. You, and your MINI, will be glad you did.
[ The premium gas conundrum ] Deltafarmpress.com
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[ Gas Testing ] dbmini.us
If you can afford to own a Mini, then you should be able to afford the fuel(premium).
The real reason premium gas is needed in a high compression ratio engine has nothing to do with there being “more” chemical energy in higher octane fuel. The higher octane fuel simply allows you to run a higher compression ratio without detonation of the gasoline and therefore preventing knock and ping. The reason why the car would feel as if it has less power is because the gas isn’t burning as the engine designer intended, but instead is detonating and therefore producing less power. Theoretically, the higher the compression ratio, the more power you can extract for a given displacement. However if the compression ratio is too much above 10.5:1 in most naturally aspirated cars you will need to run something higher than 87 octane ((R+M)/2). This is why when people start running high boost on their engines, they are essentially increasing their compression ratio, they need to run on a much higher octane in order to extract every last bit of power.
You guys are lucky, over here in the Netherlands it’s 7,68 dollar per gallon (1.50 euro/liter).
I have a compression ratio reduction from 8.3:1 to 8.0:1 but I still get premium to be on the safe side.
<blockquote>If you can afford to own a Mini, then you should be able to afford the fuel(premium).</blockquote>
When I bought my MCS, four years ago tomorrow, I was paying $1.39 for premium gas. Last week I paid $3.39 for premium. The price of gas has more than doubled while my income has remained relatively flat. It can make a difference to some…
Yea I work at starbucks and basically live off the tips we split at the end of the week and gas takes an automatic $35 out of my lunch fund
Hmmm…what about buying regular gas and topping it with the after market octane booster frm Walmart?…I know its not economically feasible…as those bottles are expensive too…just wondering if N-E 1 tried it b4….
dreamy…
Wow… that article seems very misleading. Sure it’s great that the Vette doesn’t require premium, but at the end of an equal drive, which car is going to pay more for gas? The MINI or the ‘Vette?
Also the article states the Corvette gets 19MPG while the MINI gets 25MPG, which is incorrect. According to fueleconomy.gov, the 2007 Corvette gets 14 city/24 highway while the 2006 MINI Cooper gets 24 city/33 highway. (the ’07 Cooper reports as 27/36) Even the 1996 DOHC Dodge Neon recommended premium, and this continued through the life of the Neon, and the Neon would “detune” itself if it detected regular gas which resulted in a drop of about 10hp.
<blockquote>the other a new Mini Cooper convertible with a 4-cylinder, 115-hp engine that does 0-60 in a ho-hum 7.1 seconds.</blockquote>I wish! That 0-60 is for an S. The spec for an MCC is 8.9 seconds.
What is not even being considered in the original article is hp/liter. Anyone can make 400hp on regular if the engine is big enough. It takes better engineering, and better gas, to make 400hp out of a small engine.
I do believe that Corvettes use a 367cu.in.(6L) engine and manage 400hp. A MINI uses a 98cu. in.(1.6L) to make 168hp. If the MINI were equipt with a 6L motor it would make approximately 1500hp and blow the doors off the Corvette, any Corvette!
So, take that Mr Farm Press writer!!! 😛
Oops. Sorry. Bad math. It would only be 630hp. Wishful thinking I guess.
Even the top of the line “Ron Fellows” edition ZO-6 corvette with a 7L – 505hp engine is only 72hp/L where as the MCS is 105hp/L. It is no wonder that they can run on regular. At those specific output levels they could practically run on beer.
But I guess beer is more expensive than gasoline.
Keep in mind the Corvette is naturally aspirated, but huge in displacement – they actually have similar HP/L numbers if you use an R50, but the efficiency is skewed to the MINI in a huge way, even though the smaller engine is pulling around more weight per HP. This old song has been playing since the ’60s, and it never does add up if you do the math. Premium gas would have to be at a huge price differential to make any comparisons equal.
My understanding about octane booster is “Don’t do it, because the ingredients will damage the cat”. Besides, the engine is tuned for 91 and 93. The ECU will retard the timing if suboptimal (read regular) gas is run; it ain’t gonna go like it could.
Like Gabe said, there are folks who run regular in their r53, but it’s a false dichotomy to think you are saving money with regular. Like Vanwall said, the delta in pricing is not great enough. You’re also skimping on performance.
The price difference between regular and premium has been ~$.20 for a few years now. The difference was that 3 years ago that was a large percentage difference, $1.80 vs $2.00 or 10%. Now the relative price difference is somewhat smaller, $2.85 vs $3.05.
My new R56 MCS runs fine on 87. More than likely as gas gets more expensive, making the visible difference in price between reg and premium bigger, we’ll see more and more cars that can run anything. I see that as a big selling point in all segments. We may even see higher octanes for enthusiasts as the oil companies try to keep their profits up. Twenty cents for 93 is one thing but if all cars end up running OK on 87 we could see 99 octane for a buck more, maybe?
If $.20 a gallon difference for premium pinches you financially operating an economy car–then you must be a hurtin buckaroo.
<blockquote>The reason why the car would feel as if it has less power is because the gas isn’t burning as the engine designer intended, but instead is detonating and therefore producing less power.</blockquote>
I’m no expert, but wouldn’t the lower octance gas induced pinging trigger the knock sensor, which would then cause the ECU to adjust timing? Presumably, leading to less power?
RE: iNomis
Turbo + Low Octane = Ping = Detonation = BOOM!
Just don’t do it. That 2 bucks a fill-up could cost you a new engine.
Also if you wanted your high performance car to run on cheap gas you should have bought a Yaris.
Or you could look at that 20 cents as 6.5% better economy. Or two beers per tank. 25k for an economy car is another story.
“If it don’t ping it’s not a bad thing.” I ran a tank of 87 because it says you can and I wanted to see how it did. No difference in everyday driving. Not sure what I’ll get next tank, anything but mid-grade. I’ve actually recorded better milage with premium in the past on other cars, though never as much as the percentage difference in gas price. Eventually those Hondas started pinging on regular so they required premium all the time.
>Eventually those Hondas started pinging on regular so they required premium all the time.
R50’s do the same thing on regular fuel. Or, at least mine does when trying to do anything that requires the car actually moving.
<blockquote>The price difference between regular and premium has been ~$.20 for a few years now. The difference was that 3 years ago that was a large percentage difference, $1.80 vs $2.00 or 10%. Now the relative price difference is somewhat smaller, $2.85 vs $3.05.</blockquote>
In my area, S.W. Florida, my preferred Tier 1 gas supplier, Shell has been trying to expand the pricing differential between between the grades of gas to 12 to 17 cents per gallon. The price differentials between regular and premium can run as much as 35 cents a gallon. I still only burn premium for now, but the temptation for dropping down a grade or two during non-autocross weeks is growing.
<blockquote>When I bought my MCS, four years ago tomorrow, I was paying $1.39 for premium gas. Last week I paid $3.39 for premium. The price of gas has more than doubled while my income has remained relatively flat. It can make a difference to some…</blockquote>
I don’t think the cost of gas is the question in this case, the question is the cost “premium” of premium gas over regular gas. Even when we were filling up at $1.39/gallon, premium was still usually $0.20 more expensive than regular. DB’s point is that it really doesn’t cost that much more to fill up with premium than it does with regular (~$2.50 more per fillup). In fact, it is relatively cheaper to top off with premium now than it used to be.
As this article really fails to drive home, the point of saving money on gas is overall gas mileage… not whether you use regular or premium gas. It costs about 7% (at $3.00 per gallon) more to fill up with premium than regular. So given two cars, one running on regular and one on premium, if your “regular gas” car got anything more than 7% less fuel economy (
I started my post back by BilboBaggins, took too long to post I see… Plus, I got cut off…
Anyway, just to finish the point…
So given two cars, one running on regular and one on premium, if your “regular gas” car got anything more than 7% less fuel economy (
One more try without the “less than” symbol.
So given two cars, one running on regular and one on premium, if your “regular gas” car got anything more than 7% less fuel economy (LESS THAN 27.9 mpg – as a hypothetical reference) versus the “premium gas” car (if it got 30 mpg) – then you’d save money on gas using premium in the premium car.
Or, said another way, if you get 7% less gas mileage using regular in a car that requires premium, you’re losing money trying to save money… add on the reduced performance and the damage that could result from knocking, it’s not such a great deal anymore.
As the price of gas goes up, premium actually gets relatively cheaper. At $2 a gallon for regular, premium at $2.20 is 10% more expensive. At $3.00/$3.20, it is only 6.7% more expensive (as long as most gas stations continue to play the +20 cents game, which they have been the past two summers when prices skyrocketed).
I thought the minimum octane rating in the MINI handbook says 91 RON?
Some people tell me that the car uses less fuel on a higher octane, but it comes back to the old cliche – Don’t drink Champagne on a beer income.
The knock problem is no small issue – the life of your engine could take hit if the pinging is just marginal enough to happen, but you don’t hear it, so the only issue I really worry about with premium grades is whether or not they are at 91 for real – gotta trust Big Oil there. The problem with volumetric efficiency is it likes light, fast, short movements to keep in a safe piston-speed range, and it’s hard to reconcile that with street vehicles.
If I could get 100 HP per litre in a naturally aspirated gasoline street engine, I bet it would be fairly clean running comparatively, but pretty damned expensive – all roller bearings and such to cut down on friction – and I guarantee it would use expensive grades of gas. It might even get good mileage if the transfer of power was the equal of the engine in efficiency. The closest I ever got to the magic 100 on a factory un-modded street car was a ’66 Honda S600 convertible, which got 57 Hp out of 606CCs at a redline of 9500RPM, with all sorts of race car aspects to the motor right from the factory. Kicked ass on most small sports cars, and it got pretty good mileage, too, and yup – it needed premium.
During the time I had my R53 I used mid grade, as that was what my dealer recommended. According to him, BMW claimed that the car actually performed better with mid grade, and I found that to be true. Now that I have a new R56, I have been using only premium, even though the owners manual says you can use regular if premium is not available, but it is not really recommended. However, here in Canada, the difference in price is 10 cents per litre, or 38 cents per US gallon. I consider this to be a real rip off, as I do not see how it costs that much more to produce. If the price difference in the US is only 20 cents a gallon, I guess that proves my point. Anyway, the difference in cost for a fillup is about 5 bucks a tank. However the new car does get better mileage, and the difference between premium and the mid grade I used to use is about 2 bucks a tank, and I can handle that.
It should be perfectly safe to use the minimum octane rating as mentioned in the manual. Modern engine are equiped with knock sensors, which trigger the ECU to retard the ignition. Sub-optimal power, but your engine does not knock (which will ruin it quite quickly). I’m sure that will only work up to some extent, hence the minimum rating. If you go below that, the compensation mechanism will not longer be able to cope.
As an experiment (or maybe because I grabbed the wrong nozzle at the pump), I filled my 2006 MC – CVT with 87 octane instead of premium. Trust me, don’t do it! The MC-CVT is already slow enough! With the cheap stuff in the tank, it was a SLUG. The poor little computer kept dialing back the timing to eliminate knock at the expense of “GO”. No longer would my little commuter car squirt into traffic – I was being passed by Kia Rios! It took two full tanks of Premium to get it back to it’s former self. Now I know – if some engine engineer boffin says to run Premium, then there is a darn good reason. I would guess that if you were cheap, and needed to run 87 octane to save money, that it probably won’t hurt the engine. But as other have said, if you can afford a “Premium Small Car” like a MINI, then an extra $3 to fill the tank won’t make much difference. Motor ON folks!
I wonder, if you are really penny pinching and live in a state where you pump your own gas, could you fill up half with 93 octane and half with 89 octane and end up with 91 octane? Would save you about $.05 a gallon in exchange for swiping your credit card twice.
You could then floor it on your way out of the gas station with the excuse that you have to stir the tank.
– Chad
When you fill up with “mid grade” that is exactly what you are doing. The pump mixes the regular and premium for you. In my area, mid is 6 cents a litre more, premium 10 cents more.
That’s what I’ve done with my 02 MC – half and half or mid grade if available. My 02 MCS gets 93 all the time. I get about 31 mpg and 28, respectively.
And I worry about putting anything less than 99RON in my MSC lol .. but then we do have some high prices in the UK that counter the better fuel.
Wait a second…since when does the Corvette NOT require premium? It does require premium, or you void the warranty. Sports cars have different fuel chamber designs for faster speeds and acceleration, necessitating higher octane.