Re: OBC Inaccurate

[Brett Shortland <shorty@xxxxxxxxxxx>]

>From: "R Wiles" <rwiles@domain.elided>
>Subject: OBC Inaccurate
>
>I have an 87 535is (E28) and the On Board Computer AVG MPG is nuts!  Howcum?
>I average about 21 mpg on the highway, with some around town, but the OBC
>always reads 4-7 mpg HIGH!  What can I do about it?
>
>Thanx

>R W Wiles  CLU ChFC

Here's the thing.  A gallon, to me is 4.5 litres (or thereabouts) cause we
use good old fashioned English gallons.  The U.S., to prove that they were
big boys now and could make their own rules, decided that a gallon is ~3.8
litres.
BMW in their effort to please everyone made the OBC compatable with
everyone's measuring standard.  The average fuel consumption can be measured
in L/100km, miles per gallon (IMP) or miles per gallon (U.S.)

To configure the OBC to U.S. gallons, select "CONSUM." and press the
recessed 'Set' button.  The display will cycle from L:100, MPG and M/G.  
  L:100 = Litres per 100km (duh!)
  MPG   = Miles per U.S. gallon
  M/G   = Miles per Imperial gallon  

 If you use M/G your mileage will read about 20% higher than actual.

Of course, you may just have a faulty input...


Brett Shortland
'82 535i
Perth, Western Australia  (Where if the temperature's 40, it's bloody hot!)

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