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      01-11-2013, 04:42 AM   #15
HighlandPete
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Drives: BMW F11 535i Touring
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Quote:
Originally Posted by ovekvam View Post
I think the combined factory figure does not involve cold starts. In the real world you typically start the car cold every day, which make a huge impact on the consumption, particularly on short trips.
And "conditioned" temperatures at that.

Cold starts and high electrical loads in winter can typically knock off the 10% that has alreay been mentioned in other posts. I've seen that sort of difference on seasonal changes, in several diesel engines, and that can be 5mpg or more in reality.

Just to show how a cold start and ambient temperatures affected my 330d.

From home to the next village, a trip I'd repeated hundreds of times. Reset OBC and reading at village, 3-miles from home.

Cold start around 0°C OBC reading 25-26 mpg.
Cold start approx’ 10°C OBC reading 29-30 mpg.
Warm start approx’ 10°C OBC reading 34-35 mpg.
Hot start at approx, 10°C OBC reading 37-38 mpg.

Note that is a spread of about 13mpg over the first 3 miles from a start, just covering a 10-degree ambient range. Obviously the mpg reduces the spread over higher mileage from start up, but still over a 5mpg spread at around 12 - 15 mile trips, using the above examples.

HighlandPete
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