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      01-11-2013, 06:25 AM   #19
HighlandPete
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Drives: BMW F11 535i Touring
Join Date: Mar 2007
Location: Scotland, Highland Region

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Quote:
Originally Posted by aiya78 View Post
Normally, between 70~75 and using cruise control.
Is there any problem with my driving style?
The difficulty in reading OBC figures, how accurate is the OBC?

Have you actually run any brim to brim calculations to establish your true average? You can then adjust your figures if you know the +/- error of the OBC. Then when you drive the motorway you can reset, and see how much mpg you actually are achieving at ~70mph, adjusting for any OBC error.

An E90 318d saloon driving at a contant 70mph is reported to give 53.9mpg in test conditions, so an F20 116d won't be too much above that in controlled conditiions. The 1-series doesn't do too well at speed from many reports. Some who have run both 1 and 3-series find there is virtiually no gain at motorway speeds in the smaller 1-series diesels. Aerodynamics don't help and the engine will be running a bit more boost than the 120d at that loading, so another negative.

Lowering the speed is where the smaller engine will start to march ahead on mpg.

HighlandPete
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