I always go long (14-17 gallons to fill it up) periods....well, thats usually only about 4-5 days....but still. Best I get is about 24-25mpg....I got 24.34 last night when I filled up. Most of my driving is city or 80-85 freeway, so its not bad at all. My dad's car gets slightly better but it has better fuel injectors too.

I don't think 34 is possible in a 300SD unless it was all at 45mph, with no stops, for an entire tank....and downhill most of the way. Best either of our cars has EVER gotten was 30.7 and 31.3 when driving about 300 miles @ 55mph with no stops.

When filling up with only 4.48 gallons even slightly unlevel ground could easily skew the numbers. If the car was on a very gentle slope towards the passenger side you could easily lose up to 1.5-2 gallons of capacity....bringing the mileage down to 26 even if off by 1.5 gallons. You need to run the tank down 17-18 gallons at a time.

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