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[Shelby]

Just wondering if this is the norm as my trip computer (specifically the range) is very eratic.

For example (and this is pretty much how it is each day).

I left for work this morning and it read 285 miles.  Its approximately 25-30 miles to work, and I did maybe 5 miles max around town at lunchtime.

When I left work it read 185, so I did about 35 miles or so and lost 100 miles on the range!

On the drive home, (same route, opposite direction) it was 185 when I left work and 187 when I got home.

I typically cruise in at around 60-65 on A roads then 70 on the dual carriageway going to work, on the way home 70 on dual and 50-55 on the A roads as normally stuck behind a truck or two, or three ....

I have driven many cars with trip comps and a fair few vauxhalls with them and have never seen such eratic readings before.

The fuel gauge shows less than 10 litres used in the round trip.

Any thoughts?

EDIT: I should point out that I suspect my fuel tank may not be air tight (investigating this at the moment) as when I last filled it up a few weeks ago it leaked like hell when it got full, so haven't been filling it up since, just maybe 1/2-3/4 tank at a time.  Could it be possible that I am suffering with fuel evaporation during the day (especially as its fairly hot and sunny) during the day?

[henryd]

your trip computer is using your fuel consumption to work out the range so as your journey changes,ie around town driving,your fuel usage goes up and the range becomes less then when you hit the open road again the range will get better
HTH

[Shelby]

Yes, I understand that, but I wouldn't expect my range to reduce by 100 miles after 35 miles of driving.  My average consumption has only changed by about 0.5mpg.

What I would expect to see is a similar reduction (not exactly the same) for each direction.  Obviously it would vary a bit as uphill / downhill stretches aren't the same etc.  And this is typically what I have seen with every other car I have driven that has a trip comp.

[Osprey]

AFAIK the range calculation uses your average consumption over the past few miles or minutes (20 miles perhaps?).  So your reading this morning says you have 285 miles left in the tank if you drive the way you were driving yesterday. 

The reading of 185 miles when you left work was based on your mpg rushing to work in traffic this morning plus another cold start and 5 miles of urban driving at lunch time. 

Probably a clearer run with not so much stop-start gave good mpg and brought the estimate back up to 187. 

I have noticed that if my wife uses the miggy to drive in London the range, based on London mpg, is very low.  I can amuse myself by watching the range go up steadily as I take a motorway trip, kidding myself that my smoother throttle control is what is making it look good.   
8-)

[henryd]

I leave my mid showing outside temperature,looking at range and consumption is too bloody depressing

[Shelby]

AFAIK the range calculation uses your average consumption over the past few miles or minutes (20 miles perhaps?).  So your reading this morning says you have 285 miles left in the tank if you drive the way you were driving yesterday. 

The reading of 185 miles when you left work was based on your mpg rushing to work in traffic this morning plus another cold start and 5 miles of urban driving at lunch time. 

Probably a clearer run with not so much stop-start gave good mpg and brought the estimate back up to 187. 

I have noticed that if my wife uses the miggy to drive in London the range, based on London mpg, is very low.  I can amuse myself by watching the range go up steadily as I take a motorway trip, kidding myself that my smoother throttle control is what is making it look good.   
8-)

That could make a bit more sense

Just trying to get my head around different things as I go along, I knew the car wouldn't be that economical (smaller engine - big heavy car etc), especially compared to the Peugeot 406 2.1 diesel I had previously, but am a little surprised at how bad its fuel economy actually is 

Looking at posts on here the 3.0 V6's are more economical lol.

Maybe I can tweak a bit more out of her with a good oil change (which it desperately needs) and fuel filter change (no idea if/when that was last done) etc. just a general overhaul.  Unfortunately cash is tight as it has cost me a lot since I got it (mainly due to my own blind stupidity of not noticing an obvious issue when I got it).