Quote Originally Posted by Daox
Woops missed that.

Yeah, post the numbers up and we'll figure stuff out.
Not a problem. Okay, here are some numbers. These will be in a litres/100km, Miles/US Gallon and, Miles/Imp Gallon. All numbers reported are primarily highway miles.

The BEST mileage I ever had in this car, was shortly after I bought it in 2006, which was 6.73/34.94/41.97
The worst ever highway mileage was 9.81/23.97/28.78 in January 2010. The mean temperature was around -19C

RIGHT before I did the K&N filter/spark plug tune up in spring of 2009 it was 9.61/24.46/29.38

RIGHT after I did the K&N filter/spark plug tune up in spring of 2009 it was 7.97/29.50/35.43

It was up to 7.44/31.61/37.7 at one point.

By October/November 2009, I was averaging 9 litres/100km (26 miles/us gallon).

Just to show this isn't seasonal, I was routinely getting 7.8 litres/100km average (30.2 miles/US gallon) in January of 2007!
The mean monthly temp that year was -16C