Site News - 11/22 Member of the Year Voting
Date: Fri, 21 Jul 2006 16:30:39 GMT
From: - Bob - <>
Subject: Re: gasoline grade - how important?

On Fri, 21 Jul 2006 09:14:29 +0100, "DervMan" <> wrote: >It may, perhaps more so in hot weather... but it may not! :-) > >Depending on the machine, you may notice poorer fuel consumption but no >difference in running, or the same fuel consumption but it feels materially >slower. If there's a detrimental impact on performance, this may only >bother you if you often chase the power through the gears. If you spend a >significant period of time cruising on reasonably level freeway, you'll only >notice it every so often and can live with it. The engine will knock under boost. The computer will detect this and retard the timing so that the knocking stops. SO, you will not cause engine damage. Most cars today do this. The result is that the engine does not run as efficiently and loses some power. You step on the gas pedal harder to compensate, you use more gas per mile. The additional downside to the timing being retarded in a turbo is that the boost will be effectively limited by the computer, impacting power. But, the question comes up from time to time. Most Saab testers I know have concluded that it cost them a couple mpg. The difference between regular and premium is about 20 cents, or about 6.5%. Most of the testers have found it results in 2mpg less, or about 6.5%. So, right now it's a wash in terms of $'s and you end up driving a sluggish car. Your choice... and you might want to do your own testing as Dervman suggested, see what happens to mpg, and to power. FYI - the SID is not a very accurate way to check MPG.

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