Simple existing math can get you close; for each 10*F reduction in air temp, N/A engines make about 1% more power, and forced induction about 2%. Take this number and multiply it by the rated HP of your engine. Convert that HP # to BTUs, and divide by the average BTU of winter gasoline (I believe kschachn has posted the number before). Then, calculate in divisions of 10, the temperature difference from 70*F. So, if a week’s temp was 20*F, the multiplier would be 5. Multiply that by the number you got when dividing BTUs, and that should give you a decent estimate of the overall mpg “hit” from the colder temps.Hey folks,
How much mpg do you lose in winter vs. the best of what you get in spring/summer/fall?
I don't have a trip computer in my car, but by my manual calculations I got 28 mpg in late summer/early fall and now that temps have plunged here in central Alberta, I only got 23.7 mpg on my last tank. That's a drop of about 15%.
Just wondering if this is normal/typical.
In my old 175HP Fusion and my 169HP Transit Connect this works out to about .4 mpg per 10*F drop, and has proved pretty close (when there’s been say a week at roughly the same temps). My 3.5 EcoBoost, with the ~500rwhp tune in it loses roughly 1mpg per 15* drop.
So, when we had 20* weather, I see about a 2-2.2mpg drop in the Transit Connect. The truck would drop from low-mid 21s into the high 16s-low 17s depending on remote start usage.
Maybe I didn’t explain it the best, but if you discard minor variables like tire pressure and gas energy content, I think the calculation based on air temp is probably the best guesstimate since those factors are known to be true based on many years of SAE power testing data and other power/fuel calculations. There’s no real way to calculate the overall impact. It is what it is.