How accurate is onboard computer? (1 Viewer)

[Chris51]

Often wondered how accurate is the onboard computer as average ongoing "mpg" is concerned(Relay 2,2) ?

 

[pappajohn]

Check it and see.

Fill tank
Zero MPG
Drive til nearly empty
Refill to top
Note litres needed to fill and current mileage. (Divide litres by 4.54 to get gallons)
Calculate MPG
Check against computer.

Personally I find the MPG computers a waste of time....when you need fuel, you need fuel.

 

[Wh05apk]

Overall I think the fiat one is reasonably accurate, the issue I have is filling consistently, as it suddenly fills and will spurt back, as a result, I only now fill to the first cut out, which depending on pump flow could be a couple of litres more or less than I have used.

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[chatteris]

I like to keep an eye on mpg, if it drops a lot something is wrong

 

[Xabia]

Mine is approximately 22% over optimistic on mpg.

 

[GWAYGWAY]

I do not know if it is accurate but mine says between 14.1 to 14.4 km per litre from start on a new trip per day, usually at a steady 55-60mph.

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[Wh05apk]

I do not know if it is accurate but mine says between 14.1 to 14.4 km per litre from start on a new trip per day, usually at a steady 55-60mph.

That's about 40mpg! Is that downhill all the way?!

 

[injebreck99]

Mine does 99.99 downhill !

 

[maison]

Mine does 99.99 downhill !

That’s nothing!

My last car did 999.99 mpg downhill!

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[Bart]

Mine lies to me........ Tells me i'm getting 30mpg where as I am actually getting 24mpg

 

[Lenny HB]

All three Ducato's we have had have been accurate between 0.2-0.5 mpg compared to tank brimming method over several tank fulls. Always tend to read slightly under.

 

[appydaze]

I do not know if it is accurate but mine says between 14.1 to 14.4 km per litre from start on a new trip per day, usually at a steady 55-60mph.

Not bad for your light aircraft.....

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[WillH]

Mine reads slightly under, it will show 28 - 29 m.p.g when I am actually getting 30 - 31 m.p.g. on tankful to tankful. I record all my fuel purchases.

 

[frogijock]

I never worry about fuel consumption, I look at it as,if I have to worry about a mile or two more or less from Fiats figures, then I cannot afford to run the van in the first place.

 

[Pausim]

I do not know if it is accurate but mine says between 14.1 to 14.4 km per litre from start on a new trip per day, usually at a steady 55-60mph.

That's about 40mpg! Is that downhill all the way?!

Possibly litres per 100km, which is how my Merc based Hymer measures it, and that is nearer to 20 mpg than 40.

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[Clarky]

I use a fuel app on my phone to log fills and the onboard Fiat computer seems to mirror my results. Cant tell exactly as I zero the trip so frequently.

Richard.

 

[G-RMPS]

Last October our 130hp Ducato-based Hymer showed 26 mpg for 2000 miles around Italy and Croatia. On the way home it suddenly went to 5.6 mpg. This was on both "A" and "B" journey logs. I have no idea why. I've subsequently replaced the starter battery, so the computer has reset. Any ideas?

 

[Wh05apk]

Dpf regeration?

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[G-RMPS]

Really? I didn’t even know this can “happen” automagically!

 

[Pilote87]

Your calculations are only as accurate as your speedo / odometer. In theory, therefore, you may be getting a figure which is up to 10% to your apparent advantage.

J