Computer MPG versus Actual MPG

[Bluefleet321]

Just ordered a Superb Sportline 150BHP DSG and have a question on MPG.

 

I currently drive an Audi A5 and before that a VW Passat. Both reported around 5mpg over what they were actually doing. Seems to be a VAG issue judging by other threads I read ref Skoda too. My 2008 Mazda 6 I had prior to the VW was near enough spot on so it can be done.

 

Is the current Superb any better for this and more importantly, has anyone found a fix for it? I remember asking the VW dealer about the Passat (could it be calibrated for instance) and got a flat 'no'. 

[Mattster]

There was a post in the 150mpg thread where someone was able to correct thiers, I'm finding the mpg excellent on my 150tdi manual with 60plus mpg (according to trip computer) easy to achieve, that's driving at 70 via ACC with mixture of of roads.

I don't think it's too far out as I'm currently on just under half a tank and have gone 435 miles since refueling.

[BigBadRob]

I wouldn't say its a particularly good indication; I did 300 miles on Wednesday in eco mode and returned 54.0mpg on the gauge and that, combined with the rest of the tank used since last weekend equated to an over all of 48.7mpg. In reality, it was a wee bit less than that according to the petrol pump on refill, sitting somewhere around 45mpg. I imagine if I had less of an inclination to use the sport mode for certain stretches of A road then it may improve dramatically...but I can't see that happening any time soon  

I have never had a vehicle that was dead accurate in it's reported figure on the dash but some, as you say, have been closer than others. My Fabia Vrs once told me I'd achieved an average of 64mpg on a run to the Aberdeen office (and what a boring drive that was slip-streaming trucks most of the way) In reality it turned out to be closer to 55mpg whereas my Volvo XC70 did a permanent 32-33mpg regardless of the amount of people, dogs & tools in the boot and that was fairly accurate all the time.

[skidpan]

Worst computer I have had was a BMW which read 6 mpg over the calculated. The best was the wifes Kia Ceed, it actually read 2 mpg less than the calculated.

 

So far the Superb looks reasonably close but its early days yet.

 

If you want misleading consider our Golf TDi. Calculated mpg on a holiday run was 60 mpg, very happy we were but then we bought a Sat Nav. The Golf odometer over read by 6% making the car appear far more economical than it was, did VW do this on purpose I wonder? No odometer since has been spot on with the Sat Nav but all have been pretty close especially Fords, the Kia Ceed actually recorded less miles than the Sat Nav.

[john999boy]

There is a VCDS setting which allows adjustment.

[philbes]

There are other threads on this topic.  My car is 5% optimistic on mpg.

[YS53]

Yes we have seen up to 64mpg (usually sits at around 60ish) indicated on our Fabia but I doubt that the true avg mpg figure (by brimming) is much better than 55-57mpg.

[rickyang]

I drive a very consistent route with mine over 112 mile per day, when it comes to refueling it says I've averaged 62 mpg but the actual it 59.6 so I think it is reasonably accurate and a very good indication anyway.

 

1.6TDI SE DSG by the way and I've just hit 5000 miles.

[Mike66]

Done just over 15k miles. Do brim to brim and Excel spreadsheet. 90% of refills is 6 to 7% over read on the car computer. Other 10% a bit random, some close, once under.

[daveo138]

Mine is optimistic by about 2-3mpg. It says it is doing 45, but it's really around 42 or 43. 

 

I had a couple of Passats before and they were similarly optimistic. 

 

My first Passat suffered the dreaded injector failure, as they did. When I got it back from being repaired, the mpg seemed to have improved. However, when I checked it, it was no different to what it was before, so they had obviously fiddled with it. 

[Leeboy]

My 1.4 petrol has a long term average (of 19500 miles) of just shy of 49mpg accordingly to my Fuelly logging.  The long term average on the trip computer ( which resets every 9999 miles)  is around 51 so agree with the above.  Pretty close to be honest. 

[bigjohn]

The onboard computer mpg of my petrol Superb II 1.4tsi seems to be just about the same as the tank to tank figures (+/- a bit depending on "fill click position") - about 46mpg tank to tank average according to Spritmonitor

 

The onboard computer mpg of my previous diesel superb I 1.9pd actually under-read by about 4mpg (showed 46mpg, tank to tank 50mpg) 

Edited 15 April, 2017 by bigjohn

[Warrior193]

My manual 1.4 TSI fuel computer generally indicates 2-3 MPG higher than fill to fill calculations, most mileage is for the 9 mile suburban commute to work and I usually get 400 - 420 miles per tank (brimmed). A reasonable indicator, I believe, but I might see if I can get it recalibrated when I have some adaptations done.   

[Jaytip]

I did a run with a brim to brim yesterday. Onboard showed 66mpg, working it out showed just over 65mpg. Happy enough with that.

[Rainmaker]

I stopped tracking MPG ages ago (about the first 2,000 miles as the car ran in), but my Columbus was accurate to around 0.2 MPG across fill-ups for that time. Whether that's a petrol engine thing or my driving just happens to suit the ECU's fuel metering I don't know, but it was around that figure for each and every fill up I measured brim-to-brim.

[Bluefleet321]

Thanks for the replies. Will be interesting to see how mine works out when I get it. 

[teebs]

Mine ranges from between 4-5% (optimistic) when measured brim to brim.

Can live with that