People

Just had a 2nd service at 22k miles - car running lots smoother so happy.

BUT I seem to have lost 15-20% of my fuel economy.

Used to get 40mpg now down to 33mpg!

Has anyone else experienced this / can anyone explain it?

Spoken to my dealer and they are suggesting down to UK temperatures falling in the winter - sounds like BS to me!
Help!

 

Do they use winter blend diesel across the pond? If so, it something we all suffer from during the cold months.

 

Are you using winter tires? My fuel econmy gets poorer with the winter tires, and even worse when it gets colder.

 

Naturally, an engine wears the most, and consumes the most fuel when it is cold. That's why you drive as easy as possible on the engine before it reaches optimal temps.

A mix of #1 and #2 diesel will aid winter starting, but reduce power and efficiency.

BTW, for others that aren't from the UK (neither am I, but).

His mileage figures used to be around 33 mpg US, and now down to 27 mpg.

I will use UK gallons. Seems more impressive to me.
I don't know about fuel quality over there, but in my 300SDL, I've gotten as low as 27 mpg, and seen as high as 39 mpg UK gallons. I usually average 36 - 37 mpg UK if the fuel is good in quality.

The mileage in my diesels range greatly. But are much worse if their is some type of an intake restriction.

 

My winter economy usually goes down the drain. It is a combination of warming up the car for 2 minutes before driving out, the winter tires that are like glue, and the ski racks for both of my cars.

In summer months I usually average about 15% more fuel efficiency on both of my gasoline cars. This is interesting since I always have the A/C on. The spring and fall are probably my most efficient seasons since the A/C is off and I have the summer wheels/tires (sometimes a bike rack on the roof though).

Also, your computers might need to learn a bit more and then they will get more efficient.

Steve