40.9 mpg is the best i could achieve

[Bashy]

Originally Posted by Rolvo

Yep, I guess GeorgeandKira's right, we diesel dogs do have all the fun! My fun is a 2002 V70 D5, 240K on the clock, auto box, climate control left on all the time. My wife travels badly, high speed especially bad, so even on my own I've now got a bit of a habit, on a motorway run, of sitting to the left with the lorries, cruise control somewhere between 56 and 60mph, and watching the average mpg figure get better and better.
I've had it well into the 60s mpg many times. And yes, the readout on mine is accurate - I've cross-checked more than once by doing a fuel-vs-mileage check between full tanks.
Here's an honest tale (and petrol cats will hate me for this), I once did a 90-mile early-morning run, full tank to start, all but the first few miles on a motorway at 50mph and a few gentle hills. When I stopped, the readout said 84mpg average and miles-to-empty 1,255. Unbelievable but true!
Previously had a 1998 V70 2.5 petrol, struggled to get 40 mpg, even with all the boring driving style as above, in fact I don't think I ever did manage it.

Driving at 56-60 on a motorway will return higher mpg for sure, to be honest, i wouldn't feel safe travelling with the lorries at that speed, plus, i would see issues like being slowed down all the time due to having to wait to pull out to overtake cause the other lanes will be full, this, in turn, can hurt the mpg cause of having to accelerate back up to your cruising speed.

Also, 85 miles on a motorway from a reset will be highly unrealistic, whilst it will be accurate as far as your car says it is, its far from a realistic average mpg, why, cause as soon as you come off that motorway and hit urban, that mpg score is gonna drop like a ton of bricks