Best Gas Mileage in a 200?

[maximum at weetamoo.com]

After driving extremely conservatively for a period of eight days I achieved the following and was wondering what high gas mileage figures other folks are able to get.  Trips were normal commuting, some around town errands and a 90 mile round trip to the lake house.  Passengers were my tool box and the occasional german shepard/husky mutt.  In a "normal" week I get between 22.8-25 MPG depending on all kinds of factors.  The following conservative driving yielded an extra 67 miles... granted, boring miles, but got close to two "free" round trips to the office, or almost 3 gallons of high test.

Total Miles on one tank: 518.7
MPG according to trip computer: 26.4
MPG manually calculated: 27.75
Avg. MPH according to trip computer: 38
Avg. MPH manually calculated: 38.9
Hours and minutes: 13.33
Total Gallons used, filled up at same station at same pump: 18.69.

Odometer is accurate, speedo understates about 3% (normal range).

Car is a '91 200 Wagon with 61,000 miles. Oil: Mobil 1 20w-50 has about 1000 miles on it, and car is chipped.  Tires are Michelin MXVs at recommended pressures. Probably got "into" the boost only 3 or 4 times during the entire week, and admittedly used every opportunity to save gas including not running the A/C except for a few minutes.  It's been cool in the northeast.  -Most- driving was also done during the day with temps in the 60's to low 80's and without lights on. Save the lectures about running the tank nearly dry.  Thanks.   

Paul Royal