This is my car, a 2000 BMW M5, which I love, except the fact that all M parts are extremely expensive, especially for the M5.  The only other thing I dislike about it is that I have to measure my fuel consumption in ‘smiles per gallon’ as it gets about 12mpg around town and 22mpg on the freeway if I’m lucky. . .

 I’m going to fill up my tank this morning and I thought it would be fitting to speak about gas and your BMW.  With the average price of regular gas in California sitting at around $4.57/gallon many are feeling the pinch, especially those who have long commutes or vehicles that are not fuel efficient.  Luckily I only have a 4 mile commute, so I haven’t had too much to complain about.  However, I’ve seen many BMWs complaining over the past few months about their owners choices in gas.  BMWs have strict gasoline requirements, and this is what you want to know before deciding on your own that ‘regular should be fine.’

The main determining factor as to which gas octane that your car requires is how the engine is built.  It has nothing to do with how fancy it is, how many speakers it has or the quality of the leather which covers the seats.  It mainly has to do with what is called compression ratios.  Higher performing engines will compress the fuel and air mixture more (high compression ratio) than a lower performance engine (low compression ratio) and requires a fuel that has a higher compression capacity in order that it runs correctly.  YOU MUST RUN PREMIUM GAS IN YOUR BMW.  I know, it sucks.  Regular octane just won’t cut it and neither will 89 octane.  If 93 were still available to CA gas stations, you really would want to run that.  The minimum octane that you are able to put into your BMW is 91, otherwise expect some problems.

“But it doesn’t ping at all”

That’s what I hear frequently from owners when I break the news to them.  The reason that your BMW will not ping, or pre-detonate, is due to the fact that it is equipped with knock sensors that detect the slightest amount of pre-detonation and the computers make adjustments to prevent it.  Pinging, or pre-detonation, occurs when the fuel and air mixture combusts before the timing of the car wanted it to.  This can cause major damage to your engine if allowed to continue over a period of time.  The knock sensors that prevent your car from pinging do have a limit.  At a point the computer in your BMW will essentially give up on trying to compensate for the low grade fuel you have fed it, and set off the Check Engine Light.

In San Diego I have found that the best brand of gas you can put in your BMW is Chevron, while the worst gas, from experience, has been from the different warehouse price clubs and military bases.  Everything inbetween seems to do just fine.  BUT, always premium!  I know that these days everyone is thinking about their own ‘carbon footprint’ and looking into alternative fuels and ways to conserve, but one thing will not change — you must stick to premium while gassing up your BMW.   If this is too hard to conform to, you might want to start thinking about that hybrid car or start hitching a ride with a friend.  I hate a $70 fill up as much as the next person, but I’ll never give up the handling, performance, and sheer driving pleasure that BMWs have given me throughout the years.  So for now, I’m sticking to ‘smiles per gallon’ instead of ‘miles per gallon’.

Chris Keefer

Independent Motorcars

5836 Autoport Mall

San Diego CA 92121

858-455-5836

www.independentmotorcars.com