I had posted a previous thread on why my car seemed to be getting such great gas milage per the OBC. It turned out that the OBC was way off. Several people suggested various things to adjust a fudge factor within the OBC to make it more accurate. Wiseguy suggested maybe the OBC was using UK gallons instead of US gallons. Wiseguy was right.

If I put my OBC in L/100km I find my gas milage to be 13.6. This translates into 17.3 MPG (US) or 20.7 MPG (UK). My OBC shows 20.7, indicating the computer is using UK gallons.

Thus, the fact that my navigation is now in yards instead of feet and I don't get the lawyer screen is not so great because this UK mode also seems to change the gas milage to UK gallons.

Finally, if you want to determine if your computer is using US or UK gallons you can use the following formula. Go to your set screen and change the milage to L/100km. Write down your gas milage as shown on the OBC screen. Then change your milage to mpg. Write this down too. Then divide the two numbers to determine if you are in UK or US mode.

mpg
----------- = 1.522 (UK) or 1.272 (US)
L/100km

I'd bet dollars to donuts that if your nav is in yards and you live in the US, then your gas milage looks better than it actually is. There doesn't appear to be enough range in the fudge factor to work around this either.

Oops. I messed up the formula. The correct formula is:

MPG x L/100km = 235 (US) or 282 (UK)

That's a great observation. Thanks!

The NAV computer got confused after the switching back and forth between MPG and L/100km. It is now computing UK galon!!

Originally, I got 18 MPG. Then I switched to L/100km and got 13. So far so good.... But when I switched back to MPG, I got 21.6! Ouch!!

I reset it to zero but I think it is displaying in UK galon now. I am getting very high gas mileage!

Anyone has any ideas???

David

Did your nav audio directions work with the UK mode software? I have UK mode in a new MK4 and I like the fact that I don't have the 'accept' screen, but my audio directions come across as static. TIA.

The audio instruction works very well (so far?) I have V22 software.

David

I'm in yards as well now - doesn't really bother me as I never look at the gas mileage -- too depressing. My right foot seems to be too heavy for gas conservation...

;)