I have a very strange but good experience. When I calculate the actual mileage on my 08 HCH (miles/gallons) it is higher than what the computer calculates. I always heard stories about the computer inflating the mpg numbers but mine is the other way around, not that I am complaining. Is this happening to anyone else? By the way, I'm getting over 50 mpg on my 40 minute drive to work.

 

My calculated seems to average around 1.5 mpg better than computed.

 

Known "issue"... the error range seems to be 0.5 to 2.0, always with hand-calculation being higher.

 

So what did the tank pictured in your signature calculate out too?

I always calculate higher if I'm below about 54mpg. However, if I'm above 54, I calculate 1-2 mpg lower than the computer (every time but once). That doesn't seem to be the norm around here though--even among people who get really high mileage.

 

mine seems to be 1-2mpg higher when hand calculated versus the computer - all the way up above 60mpg.

 

Delicious irony that I just posted the Excel sheet I use (See the 'Estimate my mileage' thread), but that tank would work out to 62.96mpg using the by-hand method.

 

Yeah, my hand calculations are always higher. There has been a time or two, however where it was really close.

I've heard the HCH II's system calculates lower vs the HCH I's calculating higher.

 

My computed mpg vs. the HCH's calculation is always higher, varying from very close to a 2-3 mpg difference. I find the ScanGauge is usually very close, within a couple of tenths of an mpg (although it ruins some of the fun at calculation time!). I also find a difference between the ScanGauge and the HCH's MPG gauge, with the ScanGauge tending to run higher, longer.

 

What I calculate at the pump averages 1.4 MPG better than what the dash says.

This is for 45 tanks.

 

My lifetime average displayed is 5.50 L/100 km, and lifetime actual filled petrol is 5.30 L/100 km. So the display shows a 4% pessimistic value. That's at close to 30 000 km.