My GFs 98 e300 is running low mpg city. About 21mpg city and she drives very, very conservative. The car doesn't shift over 2500rpm when she drives. The car is supposed to do at least 25 city I thought. it has 260k, no fuel leaks good filters. I maintain the car well. My 99 does 24-25 city..

any ideas?

__________________
Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k