Commuting 20 miles a day along the motorway, I aim for 28mpg if i set cruise control to 75. At 85 this drops to 26mpg. Normally aim for 400 miles between fill ups.
To be honest, all these peopel saying how they never get over 20mpg... i dont see how you can get BELOW 20mpg. I'd say if you're getting above 20mpg, then you arent driving the car long enough to warm it up properly, and you should probably be riding a bike... Big engines dont like short journeys, even a spirited drive round wales in a zed convoy I averaged 27mpg, due to it being over 100 miles drive.
Also, to those who says not a zed unless its doing over 5000rpm, again I disagree... one of the reasons I bought a big capacity engine is so I can waft along on a wave of low down torque - if you want revs i'd suggest a s2000 or an M3. I love my zed just doing 70 in top gear, cruise control on. Such a nice place to be!