Hi -

I recently purchased a 99 E300, approx. 80,000 miles, running quite well overall.

However, I've been really shocked at the poor fuel consumption I'm having, and am wondering if you all might have recommendations for what to look into to improve this.

My last tank, which was mixed highway driving (65-75 mph) and city, with A/C on perhaps 50% of the time, came out to 22.8 mpg. This seems really out of line to me.

The best I've ever seen was 33 mpg while driving at night, no A/C, 75 mph, all highway. Tires are ContiTouring Eco Plus M+S, and a bit worn but still within normal tread guidelines and inflated as per the placards.

I don't really see any smoke, and acceleration and power seem very good. I put fuel additive into the latest tank and will see if it makes a difference...but perhaps you all can tell me if this is out of line (especially the latest, mixed driving tank), and what to look into if it is. Since I've seen others posting 35-38 mpg for highway driving and lots of people claiming 30 mpg for mixed driving, the 22.8 mpg in particular seems a bit alarming.

Thanks.