My 218bhp E53 3.0d Sport Auto should (according to BMW) turn in around 35mpg but I have only ever seen this once on a long motorway run at 56mph (soooo boring!!). Normal driving usually returns around 28-31mpg and I'm a careful driver (most of the time). I would expect at least a 10-15% difference between ideal world and real world.

There have been ongoing discussions and comments in the press for years as to how unrealistic the manufacturers stated economy figures as the tests that they are required to use are equally unrealistic. No car I have owned in the last 10 years has ever matched it's claimed figures no matter how carefully I have driven. And yet the governments in Europe and elsewhere do nothing to generate a more realistic set of tests.

I have found that turning the climate control off makes very little difference on a diesel. It may be that the extra torque available just shrugs off the compressor load. There are reports in the British press suggesting that we all turn our aircon off and help save the planet. I seem to remember that if you don't use your system, the seals dry up and the gas leaks out - and it's a much worse greenhouse gas. That does not seem to have been mentioned in the press - convenient?

At least one manufacturer was recently told to revise all their claimed and published economy figures downwards as their claimed mpg was too high. Been trying to find the story but can't - sorry.

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Me:
Current: 2011 E71 40D Vermilion Red/Beige Nappa

Wifey:
Current: 2012 R80 Countryman SDX Green/Cream