How bs is your HUD mpg calculator?

**Killerteve** · 01-12-2009 07:44 PM

I've noticed with the turbo/mani/exhaust upgrades as my modding has progressed, my HUD avg mpg calculator has increased, as well as my actual mileage per tank, but they are not proportional and the HUD is wayyyyy off. Here's what I mean:

When I went Revo 1+ and a test pipe, my avg mpg on my 1000mi trip from Boulder, CO to Reno, NV got me an avg of 32mpg on the HUD, and upgrade from about 28 stock iirc. Of course that gain is most attriubuted to the TP but the actual MPG I calculated with the same setup +a K04 was about 24mpg, while the HUD was still showing 31-32mpg.

Then at the beginning of Dec I picked up the car with the 2871r elim installed (still with stock exhaust only running B3 T5). I didn't pay attention to the mpg on the way there, but on the way back my HUD gave me an avg of 42.5mpg over the whole 1k miles with and HUD avg of 72mph. When I calculated the actual MPG of the tank it was only just above 30mpg.

I don't really know the point of this thread other than to share some info, but do others find that their HUD's are inaccurate? Another thing I just remembered, also since going BT when I first fill my tank the "miles till empty" on the HUD says 650-700miles. Obviously it's full of shit but is all this related to bigger injectors? Is there anyway to recalibrate the HUD?

**dpatel** · 01-12-2009 07:55 PM

It's because you are on the gas less due to more torque available. Also it does not know you are using larger fuel injectors. It's calibrated with the stock ones.

In Hwy driving when you are not in boost, your actual modded mpg should be close to our stock readings. On the gas less but pushing more fuel than stock at same trottle level because of the larger injectors.

**cbrydon** · 01-12-2009 08:02 PM

i've got a bone stock 05 1.8t avant tiptronic usp quattro that throws no codes and has about 40k miles. my mpg has never been accurate to what is reality. i typically would be averaging about 28 mpg on the display and getting more like 23-24 in reality. i always thought it was stupid to even have this function if it isn't accurate, even on a stock car. my 91 coupe quattro is also not accurate and never has been. right now, living in the tahoe area, i am driving up and down a lot and getting not much over 20-21 mpg, but my display makes me think i'm getting closer to 25 mpg. wtf?