You guys measure the MPG only by the board computer?
I had a Prius 4 as a lease car for a year and compared the MPG the boardcomputer told me to the actual litres I tanked and kilometres I drove over a substantial amount of time and distance and to my surprise the board computer was lying to me ...
It told me I had a MPG of 70 while I actually found that when I calculated correctly I got only a MPG of 55

My Voyager has no board computer so I calculate by trip counter and how many litre I need to refill. Most accurate way methinks, and best I got was ~35 MPG. I think I could be able to get it to like 37-38 but thats about it, and my 2.5 CRD engine runs like a clockwork..
I can't imagine a 2.5 CRD getting 45-50 MPG or is there something wrong with my engine?

 

I tried the fill up method once, the result was comparable to the computer so never bothered again.

I figured even if it was 10% out, with it normally saying 33, it was either 30ish or 36ish.

When it had a partially seized brake, the computer went down to 28 so it definitely works to a certain extent.

There's no doubt your way is most accurate though, I'll give it a go again over the next wee while.

 

I've found with mine it over estimates the amount of petrol used. Although up until recently I ran mostly on LPG/Propane so the computer doesn't register it at all. However, during a recent trip down to Devon and back the computer showed an average of 21.7 MPG over the 10 days and 1100 and something miles however, my real world calculations showed an average of 24.2. However, something I have discovered is that the longer you go between resets the more inaccurate it becomes. Although, my cousin had a 2004 or 05 CDR and it went the other way under estimating his real world consumption and sometimes by quite a margin.

 

I made two large trips yesterday (380 km) and today (570 km)
Lot of highway traffic (average 120-130 km/h) and 10% city traffic
I averaged 11.5 km/L = 25.87 MPG .. hmmm.. I expected better MPG..

 

The UK gallon is 4.54 litres
The US gallon is 3.78 litres

- which is it reading ?

 

@QinteQ, you just got me thinking. I have my computer set to MPG. I wonder if that is UK or US? Hmmm

 

LOL
Ok... I know UK people and Americans are very reluctant to conform to world standards but both using different standards on such archaic measures is beyond strange.

BTW I looked it up: beside US and UK there are 2 more countries in the world reluctant to conform to The "international system of Units" : Liberia and Myanmar...

 

HiYa AlanC.

I had a fiat for a decade, it was well known in the community [brim tests] that their MPG readout, miles to empty etc was reading kilometre's but displaying them as MPG.

 

I hadn't though of that. So recalculating my trip in US gallons puts my actual mpg at just over 22 which is close to what the commuter said I was getting.

 

Well technically both the UK and US have gone metric, BUT, most people don't use it because its not what they're accustomed too. On a conceptual lever, I don't think in metric terms. If someone said to me there's a 1kg carton of butter in the fridge, I'd have to do a quick mental calculation converting into pounds so as to conceptualize what that 1KG carton is going to look like. Therefore I guess I am resistant in that I don't want to put the effort into reprogramming my brain. LOL!