Date: Mon, 3 May 2004 08:32:08 -0600
From: "Zon" <johnnospamy-to-group.please>
Subject: Re: Fuel consumption figures computer wrong


"David Taylor" <djtaylornospamoot.com> wrote in message news:MPG.1afcd1a77dff6437989c23nospam.individual.de... > > then you're lucky or manage to drive identically every single time! How come? > I haven't reset mine in a couple of thousand miles and it says 31.2mpg. > Of course that's averaged over that 2000 or so miles so if I now go and > drive hard for half a tankful, i'd expect a much higher error than 1.5 > litres per 100km. That is not an error then. You are measuring different things, and thus cannot tell anything about accuracy of your computer. > Similarly, resetting it for every journey (unless they are significant > in distance )isn't accurate because you're filling a small amount for a > small mileage and filling from a pump whose accuracy is unknown to you > and could introduce errors and you can't be guaranteed of the click off > point of the pump either. That's right. However, gas pumps are fairly accurate and inaccuracy of pump does not really matter if you measure over longer period of time & distance (large number of fill-ups), because errors average out. > Like I said, either you're lucky or drive identically, either way, the > display is a calculation which is averaged and therefore can't be taken > as absolute. What I did was that for over 10tkm I recorded every single deciliter of gas I put into tank. I also reset computer at fill up but nowhere else, and I recorded also those readings. The rest was simple math. Computer and gas pump agreed within couple percents at every fill-up, and errors averaged resulted to less than 1%. Which means error has no offset and just a small deviation. BR:Z

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