Fuel Mileage/ Ambient Air Temp - Diesel Forum

three turbos · 03-05-2010, 09:33 PM

Has anyone seen fuel mileage vary due to outside air temp? I have noticed my fuel mileage is always less in the morning on my way to work versus then on the way home, my driving style is the same I have made sure of that.I live in IL, so the mornings lately have been around 20-25 degrees in the morning to about 30-35 degrees coming home and its always more coming home.However today hit almost 50 on my way home and my fuel mileage was way better than on my way in.Yes I take the same route,same speed,same rpm I use the cruise anyone have any ideas or am I loseing it?

**MikeL46** · 03-05-2010, 10:48 PM

I see a similar thing, but its not exactly the ambient temp. It is due to the amount of time it takes to warm up the diesel. And in the afternoon the engine still has some heat in it from the morning run, and the air is warmer so it warms up quicker.

Using the ScanGuage I can see the mileage on the fly. After warmup, ambient temps do not affect mileage enough to notice. But, boy that cold engine uses alot of fuel.

Mike

three turbos · 03-06-2010, 09:52 AM

Thanks for the info. I keep my truck pluged in overnight so im usally warmed up pretty quick in am i will have to take notice in the am when i am close to the end of my 1hr commute if the mileage seems to be better than say within the first 20 miles or so.When i get to work the first thing i do is plug it in where it sits for about 8 hrs plugged in verses the 2-3 hrs its on due to a timer at the house.Well have to do some more sudying on this,guees i should be looking forward to summer if this is the case.anyone else have an op on this?

**MikeL46** · 03-06-2010, 12:12 PM

I also have a 20 mile commute.

On cold mornings I'm lucky to average 12mpg for the trip. After 10 miles, it is just up to 10mpg. 14-16mpg on the way home. 10mpg after just a couple of miles.

16mpg going to work if I plug it in for 3+ hours.

I suspect synthetic oil might help also because the cold engine doesn't have to work so hard just to turn over.

My gas engine pickup doesn't lose near the mileage on cold days.

Mike