2003 S60 with manual transmission, non-turbo, front drive.

Best: 34-35
Average: 31 over the life of the car - 114k miles in 8 years -- mostly highway, but I lived in downtown Boston for 4 of those 8 years.

I don't hypermile, but I have good driving habits and keep the speed down. You can get immense improvement just by keeping below 65, pumping up the tires, and keeping your foot away from the brake pedal.

Tires at 36psi. Winter tires are Nokian Hakkas that are low rolling resistance and get actually better fuel economy than the summer Michelin Primacy (which gets mpg comparable to the Michelin Energy that was stock on the car.)

There was a guy on another Volvo forum back in 2003, maybe turbobricks, that was hypermiling on an '01 or '02 S40. He was getting in the high 30s and sometimes as high as 40. Good luck. But get a Honda if you're serious about it. I used to get over 50 on a base model '94 Civic.