I recently purchased a 2003 HCH and have always just assumed that the mileage displayed was correct. Last night on the way home from work the Low gas light came on, and the display showed 49.9 mpg. Based on that, and knowing I have a 13.1 Gal US tank, I figured I would be able to go about 650 miles on the tank (50*13=650). The odometer showed 585 when I finally filled up. By my calculations I should of put about 11.5 gals but put in 12.7. Thats 46.0

 

This is well documented here.

I had an 04 HCH for two years.
The calculated MPG averaged about 3 MPG lower than the reading on the dash.

 

And '06 models seem to have the display reading 2 mpg UNDER true calculated... at least that's how it's been for my three tanks, and in other posts I've read! I've used the fill-it-to-the-neck method for all tanks, so I know it's 100% accurate (not subject to click-off points from different pumps or level position of the car, etc.).

 

I have filled by 5 tanks to "first click" and have consitantly seen the trip display read low by between 0.2 and 1.5 MPG. Not a huge amount.

 

8200 Miles...many tanks, but not as many as the Sub. Most of the time, we are running the same as Ikewin. But we had four tanks in a row where the reading was about 6-8 MPG lower than calculated. Then, on the fifth (last) tank, it was off by 1.5 MPG again. Now, I can understand one tank being high and the next low, but this was four tanks in a row. I always go three clicks. Strange...

 

I've tracked this for about 20 tanks now (10K miles). Average is about 3 MPG off, always on the high side (I have an 03 as well). It has varried from 1 to almost 5 off, and has never been exact since I owned it.

 

My gen one 2005 MT HCH shows 64.3 lifetime MPG but the calcs show "only" 61.8 MPG.

 

my Jan got hch has well over 12k on her (yes, its a "she") and had many fillups... how many? well, about 21-22, I really dont keep track of them anymore. All the time I do like a lill math at the pump, my dash readings are always lower by 3-4 mpg... It's already custom to have like a per tank 53 mpg in average, that translates in about 55-56 mpg real. I did a comparrision with my gps logger, to see if there is any notable difference in the distance, for a 600 miles, difference was 1 mile and 600 yards between the A tripmeter and GPS logger. I asume that's kind of ok. and everything is almost acurate...

 

I have 18 tanks. My calculated MPG has consistantly been approx. .9 to 1.4 MPG better than the display shows (Trip B for lifetime MPG). For 7,800 miles that's fairly close.

 

My 04 hch FE display is sometimes over, sometimes under, but never by more than 10%. Seems pretty random, especially since I fuel at the same station from the same pump nearly every fill up. The FE display is just not that accurate.