Do I need the expensive gas???

What you say is true, as applied to cars that require the higher octane, i.e. those with high compression and advanced (or variable) timing.

But for some car engines that have neither high compression nor variable timing via the ECU, a lower octane gasoline may actually produce more power and better efficiency.

-Fred W

Your engine has a knock sensor which will allow 87 octane by retarding the timing. But your performance and fuel economy will suffer. You might want to run a few tanks of 87 and scrupulously record your actual mpg (not from the OBC but miles divided by gallons) - then do the same with 91 or 93 octane & compare the cost. I suspect that you'll discover only a small price advantage, if any, to using lower octane.

Tom

Now that's a good thought. Must admit that my adversion to putting any "mystery" additives into the oil or gas for my cars has prevented this thought from even occuring to me.

Frank

That and the octane boost stuff costs more than the ~ 10 cents per gallon more that you would pay at the pump for the higher grade fuel in the first place.

-Fred W

Of course, otherwise everybody would just use that instead of buying premium. But, as a spot fix for a bad tank of gas, it's much cheaper than draining and refilling.

-Russ.

You bought a $40,000 car and want to save $5-$10 a week by running cheap gas?? Pack a lunch one day a week and put in the right stuff!

You bought a $40,000 car and want to save $5-$10 a week by running cheap gas?? Pack a lunch one day a week and put in the right stuff!

This is a common response that seems rooted in some sort of snobbery, of which I would reply:

Yes, but the $40k paid for a car (with particular attributes) that can not be had at less money. If there are no benefits of the costlier grade of gas and it cost >$500 per year for life to spend that money would be foolish. That is why the question is so often asked.

If the car calls for the higher grade there is a benefit and the correct stuff should be used. If it doesn't (as with all 3 of BMWs that call for 89AKI) then using the highest grade, unnecesarily, is just throwing your money away.

-Fred W

The issue is whether one can/should use a grade LOWER than recommended by the manufacturer.

DAS

For direct contact replace nospam with schmetterling

You're better off spending the money on the premium gas and instead, spend your time to check your tire pressure every week and use the cruise control as much as possible to gain the computers fuel economy capability. It can maintain a constant speed better than you and thus can optimize your fuel consumption.

rtt

Another thing. If your car requires 91 and the gas station pump only offers 89 and 93. Can you fill it half with 89 and half with 93? 89+93 /2 = 91.

sure, but is it really worth the bother to save what amounts to $1. (10 cents x 10 gallons, assuming 20 gallon total fill).

-Fred W

It's human nature. In Rolls-Royce forums, they have recurring debates on how to use cheaper, non-factory oil filters to save about $20 a year. Emanuel

E Brown wrote in news: snipped-for-privacy@4ax.com:

You don't get rich by spending money needlessly.

The non-M BMW engines will run fine on regular, albeit the ECU will roll back the timing and performance and mileage will suffer. When the premium "premium" was 20% of the cost of gasoline, this might have been a reasonable sacrifice for the lower fuel cost. With Regular running close to $3/gal, $3.20/gal for premium (roughly 7% more) the issue isn't as clear.

I've yet to see an analysis where this was broken down into dollars and cents (at what cost benefit does the performance sacrifice make economic sense).

If you're middle class and want to acquire wealth, you're better off buying a nice used Honda or Toyota (for cash) which will cost considerably less than a Bimmer and will also cost considerably less to maintain. The price difference between regular and premium is a relatively minor issue on the overall cost of car ownership.

R / John

It would be nice if BMW would publish automobile power figures at different octanes. My new Beemer (R1200RT) specifies 110 hp using 93 pump octane, and

101 hp with 87. So if the 8% drop also is consistent with gas mileage and is consistent with auto engines, then the additional 7% is well worth it - but that's a lot of "ifs"!

Tom K.

Exactly, but people in the U.S. see gas at $3.00/gal. and freak out.

Road & Track (May, 2006) tested a Camry V6 (26.3 mpg) and a Camry Hybrid (37.3 mpg), and concluded that it would take about 100,000 miles before the estimated $3,000 hybrid price premium was recouped (The hybrid is 1 second slower to 60 and in the 1/4 mile).

Tom K.

Yes, but you feel so good knowing you're minimizing your consumption of a finite resource. Oh! Wait! The guy next door just brought home a brand new Excursion. Between the two of you, you average 18 MPG!!!

R / John

True, but frugality would preclude buying a Rolls-Royce in the first place. According to "The Millionaire Next Door," most of the wealthy drive Camrys and Lincolns, iirc. The real issue is this: BMW's are the "ultimate driving machines." Why pay a premium for the car's performance and then blunt it with cheap gas, or cheap anything for that matter? It's working towards contradictory goals. epbrown

-- "Everybody wants a normal life and a cool car; most people will settle for the car." Chris Titus

2003 BMW 325i Black/Black, 2003 BMW Z4 Black/Black