# Cold weather efficiency



## BlueC (Jan 13, 2007)

hlc1213 said:


> Perhaps mine is just screwy. I just started using Fuelly for my last two fill-ups and noticed the discrepancy when comparing the two numbers. Either way, I'm gonna just ignore the onboard for now..


I've noticed mine can vary a bit. Best to rely on actual calculations.


----------



## Michael47 (May 9, 2014)

mattebury said:


> I know one of the diesel pickup truck tricks is to block the radiator. Does BMW have a custom block off piece,Doris this something that you'd have to put together yourself. I know some Dodge guys that just use cardboard on the back of the grill, maybe leave 20% - 40% un-blocked.


You are not driving a diesel pickup truck. Blocking off the radiator will only get you engine overheating and you do NOT want to go there.

Don't even think about it. Bad, bad, bad idea. Fact, every machine ever built is optimized for particular operating conditions. Any other conditions are going to result in decreased efficiency. Your 328d was designed for temps between oh, 60°F and 90°F. Get used to it. Put up with the inefficiency at 10°F. It won't kill you, but you could kill your car if you block off the grill.


----------



## John Galt (Jul 21, 2012)

You also need to take into consideration the anti-gelling additives in our MN and regional diesel, which certainly affects MPG. I see a slight drop in MPG but not as much as you have, although my X5 35d had almost 35,000 miles on it during the coldest part of the winter. I travel to remote areas of the Dakotas, Iowa and WI in addition to MN, and my X5 sees some EXTREME cold. Don't worry though- if it didn't break in the cold of this winter (mine did at 27,xxx miles due to a frozen sensor in the diesel exhaust re-circ system), you're golden.

-John


----------



## Hoooper (Jun 17, 2013)

Michael47 said:


> You are not driving a diesel pickup truck. Blocking off the radiator will only get you engine overheating and you do NOT want to go there.
> 
> Don't even think about it. Bad, bad, bad idea. Fact, every machine ever built is optimized for particular operating conditions. Any other conditions are going to result in decreased efficiency. Your 328d was designed for temps between oh, 60°F and 90°F. Get used to it. Put up with the inefficiency at 10°F. It won't kill you, but you could kill your car if you block off the grill.


The radiator is designed to be capable of cooling adequately when it's over 100 and the A/C is on. Blocking part of it when the temp is 10F is hardly a risk. There are several 335d drivers doing it in the winter.


----------

