Worst thing you can do, cos the engine is operating inefficiently when its off boost, if you floor the throttle from low revs in too high a gear, to accelerate up a hill say, you’ll burn more fuel but less power will be produced (and therefore it won’t accelerate as well) as if you changed down to get the engine into the turbo zone and hence nearer to the peak torque figure, where a much smaller throttle input will have a much more marked effect.
Key to driving diesels economically is of course planning ahead. NEVER EVER touch the brakes unless you absolutely have to, and accelerate briskly and keep the engine in the powerband, use as much as about 2/3 max revs (if your engine revs to 4500rpm change up about 3000rpm) but accelerate up to cruising speed pretty quickly, then chug along in top at minimal throttle input.
My astra is listed as 55 mpg. It goes up and down the motorway for 65 miles each way at 55 ish mph and returns 63 mpg.
That’s not surprising at all, but I’m sure if you do some town driving and a few stop start shorter journeys, you could bring that figure down under 40mpg easily. I had a 57 plate BMW 320D as a company car a couple of years ago, it had 177bhp from its 2 litre engine and 295lb/ft of torque, yet it also had astronomical gearing. If you gunned it, it was a pretty rapid car (0-60 in 8 seconds, 150mph top speed!) but of course you could get the consumption down into the low 20’s or even the teens if you tried hard enough. But stick it in 6th (37.5mph per 1000rpm in top), cruise control at 65mph on the motorway in the slow lane, and it would return 70mpg on a cruise!!!
