[Lucky]

My 2000 S averages 20 mpg in mixed use -- 60-70% back roads/in town, 30-40% highway. All quite spirited... it is a Porsche after all.

I've never taken it on a long highway trip, so I can't give a scientific # for pure highway. Based on my average, however, I think it achieves around 25 mpg at reasonable speeds.

What I find surprising is my 1986 Carrera 3.2 achieved slightly better mpg on my commute -- in the 21 to 22 range. It was smaller, lighter, less powerful, and had narrower tires (in back) which probably explains the difference.

Then there is my commuting appliance -- civic hybrid -- average 42 mpg, but ideal weather (60's, dry, no wind) mpg is in the low 50's.