Seasonal fuel consumption

[mattsurf]

We all know that Air Conditionning reduces fuel consumption. Over the past 4 years and 64k miles, I have been monitoring the fuel consumption of every tank of Petrol / Diesel. The cars in question are a Mercedes E280 and a VW passat 2.5 TDI

The average consumption by season:
Dec - Feb (Winter) - 31.9 mpg
Mar - May (Spring) - 29.8 mpg
Jun - Aug (Summer) - 29.0mpg
Sep - Nov (Autumn) - 29.8mpg

Overall the average is 29.9mpg
The worst month is August - 26.8mpg
The best month is December - 33.4mpg

It was a surprise that the difference between the best and worst is almost 20% difference.

Another interesting observation is that the Mercedes shows less of a difference than the VW (14% Vs 22%)

I know that this analysis has little practical value, however, I found it an interesting observation none the less

 

[230K]

Hi

I get the opposite with 1998 E300 TD. My mpg gets noticably better in the warmer months although i only use aircon when required.
I have put it down to winter fuel and lights etc being on more often.

Thanks,

230K

 

[Shambolic]

I use more fuel in the summer but that may be the driving really fast with the roof down wind in the hair that i dont do in the winter months(as Much)

 

[whitenemesis]

Hi

I get the opposite with 1998 E300 TD. My mpg gets noticably better in the warmer months although i only use aircon when required.
I have put it down to winter fuel and lights etc being on more often.

Thanks,

230K

Me too, much better in the summer. I leave the aircon on all year. Never noticed any savings when switching it off, this car and previous.