I'm seeing nowhere like the figures in xreyuk's signature at the moment. I've changed my working hours and always seem to be late for everything, so my eco driving seems to have fallen by the wayside in favour of dashing about in a panic...
I don't speed (much), but I'm not concentrating on the relaxed, smooth driving style that is the key to the highest mpg figures.
I got 56mpg average over the last tank full.
I'm sure there are a few other posts with tips for maximising mpg, but here is a quick summary:
- Don't accelerate or brake harshly, but don't accelerate so slowly that you're dawdling in lower gears forever either.
- Use decent fuel. I stick to Shell because I think it's good fuel (and I collect their points and they accept Amex, so I get even more points).

- Don't bother with 'super diesel' fuel like Shell V-Power Diesel. Unlike super-unleaded petrol, which I think works well in TFSIs etc and gives extra economy to balance some of the cost premium, every super diesel that I've tried has delivered worse economy than the regular diesel equivalent (and costs loads too!).
- Try not to brake at all. I don't mean that literally of course, but for your regular routes, learn the road so that you don't need to dump excess speed as heat (via braking) for corners etc. If you aim not to brake, you will learn not to accelerate more than you need to.
- Use the slow lane. In heavy traffic, you will use a lot less fuel if you avoid the constant heavy acceleration and braking of the fast lane. You'll feel less stressed that way too.
- Clear out the junk from your car - roof bars/racks are terrible for economy but even having junk in your boot will cost you fuel as it's extra weight you're having to shift.
- Try to keep your engine load constant, rather than your speed. So, if you're traversing a series of valleys and peaks in the road, allow the car to accelerate downhill and slow down uphill, while keeping your right foot as steady as possible. (Note that this is the opposite of what cruise control tries to do: braking downhill and flooring it uphill, with the aim of keeping speed constant...)
- Where sensible, travel at around 60mph in top gear. Much more than that and you'll be wasting fuel to overcome aero drag. Much less than that and you'll be labouring the engine (also wasting fuel!).
- Don't believe your car's computer - use an app like Road Trip on your phone, or just a calculator/spreadsheet, to work out your *real* mpg, from full tank fuel amounts and odometer readings.
Hopefully some of that will
help you improve your figures!