MFD Fuel consumption accuracy

**mike6265** · 15-02-2011,08:38 PM

I have a new Passat Estate B6 2.0 TDI 140PS DSG
The MFD Average fuel consumption on this car is about 14% optimistic
i.e MFD 49.1 mpg - actual mpg 42.9
MFD 52.9 mpg - actual mpg 46.5
each time measured over about 250 miles

Previous Passat B5s have been reasonably accurate

This seems a stupid question but is it possible to "tweak" the system somehow? Otherwise I will just live with it.

(I suppose the speedometers are about 10% high and we don't worry too much about that).

**kite** · 15-02-2011,08:52 PM

I believe it can be adjusted with VCDS

**Pit Dweller** · 16-02-2011,12:02 AM

It can. 10% either way

DSG4ME · 16-02-2011,03:15 AM

On a 50 mile+ run, it's within 2mpg, other use will need to be seen on settings 2 as an overall.

**bobwmac** · 16-02-2011,12:38 PM

My B6 has has now travelled some 12000 miles and have learned not to trust those fantastic numbers which appear on the screen. I keep track of my fuel costs using MS EXcel and MS Money and since birth, the car has achieved 55 mpg. The car thinks it has an overall mpg of 57.

Where's the other 2 mpg gone?

**g-black** · 16-02-2011,01:45 PM

I've found the same. I used an iPhone app for my figures and there different to the MFD. My brothers mk5 GTI is the same, always looks like your doing better than you really are.

**johnloaderuk** · 16-02-2011,01:56 PM

Mine over estimates but as with others here only by 2 mpg, which is fine with me, more than close enough.

**PeteK** · 16-02-2011,06:10 PM

On my B5.5 I used to fill the fuel tank to the brim (literally getting as much fuel in as possible) and always found the trip computer over read by 5% compared to the actual figure. However I now fill it until the pump first shuts off and the figures are very accurate.

**Pit Dweller** · 16-02-2011,07:58 PM

Correction on original post. Checked today and can be tweeked by 15% either way.

**Teflon** · 17-02-2011,10:16 AM

If you do a direct check of true speed versus indicated on the speedo or the cruise control, you will find that it over-estimates by about 5mph at motorway speeds. You can do the check with a Sat-Nav or by counting and timing the marker boards by the hard shoulder. On my car it equates to 6.7%.

Maybe this deliberate safety feature also manifests itself in the distance/mpg calculation as well?