mk2 jazz avg mph/mpg readings

[trevg]

whenever I check the avg mpg on  the computer it always reads 50.4.mpg. the same with  avg mph it always reads  31 mph. has anybody had similar experience.

[John Ratsey]

I recall that the vehicle stores different values for Trip A and Trip B. How many miles since you last reset that trip for which you are getting apparently constant mpg and mph?

[trevg]

maybe that's the problem, I have never used the trip counters. I thought it was an ongoing adjustment as you travelled. maybe I should consult handbook. many thanks for your reply. 

[JohnAlways]

I've set my "Trip A" to reset whenever I fill the tank which also has the effect of resetting the AVG Mpg display.
Trip B cycles on as I don't use it unless I'm off to France where I leave it to record the total driven miles in France just for info on return. Trip A just resets when I refuel.

[peteo48]

I reset A when I refuel because I keep a detailed record of my fuel consumption using the brim to brim method on Fuelly.com. I have left B untouched for the last 3,500 miles and it doesn't vary much at all because a one off refuel won't make that much difference.

[trevg]

yes once I  zeroed both the trips it worked perfectly. thanks for all your input.

[guest6425]

I'll add that according to my findings on recording mpg and comparing to the computer, it's not actually too inaccurate, averaging perhaps between 7% - 10% error (more) and I may find if I was brave enough to actually empty completely and use a spare fuel can, it might well be more like 5% - 7%

Because 10% is an easy number, go with that, so if your car is saying 50 mpg, it's probably more like 45 mpg.

[peteo48]

Just looked at the overall mpg reading on my trip B and it's showing 49.5. My "real" mpg is 44.2 so, yes, 10% out over a distance of 3,500 miles.

Once you know that you can work with it. I only keep the detailed brim to brim record because I'm a bit OCD and I like graphs and piecharts lol.

[guest6425]

Interestingly the reserve (yellow light) is 10 litres or ... 10% as well, it may be the computer is almost correct, I haven't been brave enough to completely empty it. Best was 20 miles beyond the yellow warning on the dashboard, I believe in theory you can get 30 - 50 miles.