how much does your OBC lie about mpg?

[golfdsg]

My OBC has been lying to me for the last few fill ups.

I already knew the OBC isnt 100% accurate but mines been telling me 49mpg and when worked out manually its 35mpg, in a 1.9tdi golf doing all short journeys under 4 miles. Not impressed

[Jasandjules]

Think mine claims around 51/2 as a rule, I tend to get about 48 I think if I calculate it out.

[5lab]

golfdsg said:

My OBC has been lying to me for the last few fill ups.

I already knew the OBC isnt 100% accurate but mines been telling me 49mpg and when worked out manually its 35mpg, in a 1.9tdi golf doing all short journeys under 4 miles. Not impressed

your mpg might be accurate - it might not be counting the fuel burned whilst stationary. My car flips from mpg to gph when stopped - I don't know if it affects the overall or not

[Alfahorn]

Mines not too bad. I think it's about 0.5mpg out, my old car was about 3 or 4 mpg out.

[jbsportstech]

Vag cars seem the worst in my experience.

Most cars a find 2mpg keen vw/audi/ skoda seem to be a little more optimistic up to 8mpg in my experience

[greendiff]

under reads by as much as 50% and over reads as much as 30%.

Basically useless!

[jbsportstech]

golfdsg said:

My OBC has been lying to me for the last few fill ups.

I already knew the OBC isnt 100% accurate but mines been telling me 49mpg and when worked out manually its 35mpg, in a 1.9tdi golf doing all short journeys under 4 miles. Not impressed

In fairness to your golf short 4 mile trips are not the best from premature engine wear and diesels especially need yo get up to operating temp and in 4 miles it won't. You might be better off with a petrol.

For a diesel to stack up you need to be doing 20-30 miles please a day.

[Drive Blind]

Fabia vRS with the BLT diesel engine. A real 55mpg would show anything between 65 and 75 on the computer. It would also claim to do 750 miles to a tank - the reality was 550 tops.

[sparks_E39]

Within 1 mpg on my 530i.

[golfdsg]

Drive Blind said:

Fabia vRS with the BLT diesel engine. A real 55mpg would show anything between 65 and 75 on the computer. It would also claim to do 750 miles to a tank - the reality was 550 tops.

Happened to me too, planned a 550mile return trip, filled the fuel tank right to the brim, OBC predicted 800 miles, but only did 550 miles. not complaining that it drinks fuel, just saying the obc is very inaccurate.

[A900ss]

My 520d was over reading by about 5% until I went into the hidden menu to apply a correction factor. It's normally accurate to with 0.3 MPG now.

[Panda76]

Under reading. Showing ridiculous figures like 28 when the actual was mid 40's. Again it's Bmw obc so went into the computer to adjust it. Now accurate to approx 0.2-0.3 per gallon.

[FRMATT]

Drive Blind said:

Fabia vRS with the BLT diesel engine. A real 55mpg would show anything between 65 and 75 on the computer. It would also claim to do 750 miles to a tank - the reality was 550 tops.

I get almost exactly the same from my BLT engined Ibiza. On average it is about 15% out

[Fartgalen]

People generally complain about Volvo OBC's being out on the average consumption, but IME they've been within about half an mpg. Last time I checked my S60 over a very long stretch, it was showing up 0.1 mpg on the OBC, from actual.