Is the trip computer honest MPG wise?

[GTXJez]

I get 27 mph per 1,000 on my HPi GTX 2.0 i.e. 81 is 3,100 rpm, lower than I think is needed, as there is good torque from the engine, and would handle longer gearing?
So sounds like the 2.0 Petrol's have similar final drive ratios to the HDi 90.
We had a D8 21.TD Estate Family LX and that was 90mph at 3,000rpm....

My Computer reads 36.3 almost all the time, but goes up to 38.2 or even 40.2 on a leisurely run.
Overall I would say 37mpg overall and if anything the computer reads slightly low?

[martint]

my (90) gives me 46.8mpg & everytime I've done a full to empty check its been spot-on 90 odd percent right!and thats around town.goes upto 50 odd on motorways!

[OdinEidolon]

my (90) gives me 46.8mpg & everytime I've done a full to empty check its been spot-on 90 odd percent right!and thats around town.goes upto 50 odd on motorways!

I had the first refueling the other day and got 55MPG with my 2.2HDi. That's with 400km of motorway at a steady 75mph on the speedo and around 200km of mixed driving between urban and country roads.
I'm astonished!

[GTXJez]

Don't be! thats is par for the course... our 2.1 TD D8 Estate did 50mpg with ease...

Wish I could get that from my GTX HPi, but I do have a very smooth and quiet engine with superb performance, arguably better handling due to the lighter engine, so a trade-off really - one that I am very happy with

[ZilogJones]

I've only filled the tank once in my HDi 90 so far, by my calculations I got 46 MPG but the trip computer was saying 41. Mixed driving (average speed 45 km/h), very little motorway or dual carriageway. I haven't been driving it that long and it's my first diesel, so I'm sure there's room for improvement...

http://www.spritmonitor.de/en/detail/448462.html

[OdinEidolon]

actually I'm getting around 48mpg with 75% highway driving, 15% country roads and 10% city, but my MFD reports around 56mpg, so I'm a little disappointed.

[OdinEidolon]

After 2000km I can tell the trip computer lies a bit. In my signature you can see my actual fuel consumption numbers; the MFD says 21km/l.

[ZilogJones]

About 1600km later it's still the other way round for me - I'm doing about 7 MPG more than what the trip computer is telling me.

[RayneR]

...snip...
regularly get mine to read "----" going downhill (infinity MPG ) and I've had single figures going uphill when cold , mind you I do live in "the Valleys" so our hills are proper hills

Of course it'll read --- when going downhill at over ~1500rpm: the engine will cut-off fuel and the car will consume zero.
It's a normal fuel saving feature introduced at the beginning of the 90s I think.

By the way I live in the Dolomitis so here we have proper mountains, not hills... i'ts a pain to read 30l/100km on the MFD.

In my 2.0 110bhp, when it's engaged and doing downhill under 30km/h or more the MFD shows in the instant consumption : 0,0l/100km , but if i disengage it will start reading, 1,5 ; 1,8

[martint]

they tend to be spot on! ive had 4 406hdi's & everytime they are exact.
currently getting 50.4mpg around town in my (90)

[steve_earwig]

mine says something really depressing right now but it's because i can't drive it for more than about 10 minutes without my back giving me gip and it's just doing microscopic journeys

DRIVER PHYSICALLY DEFECTIVE

In my 2.0 110bhp, when it's engaged and doing downhill under 30km/h or more the MFD shows in the instant consumption : 0,0l/100km , but if i disengage it will start reading, 1,5 ; 1,8

that's because when the engine revs are high and you're not using the throttle the engine management cuts the fuel off, so going down a hill using just the engine to slow the car down you're saving fuel (and brake pads...)