I've had my S-Type V6 3.0 since April 1999. I run it with ACC on permanently and have averaged 23.5 mpg overall. Best I can get is on motorway driving when the car returns around 28 mpg. Town driving around 17 mpg. These figures are not based on the trip computer which gives a somewhat more flattering view of consumption. I've kept an Excel spreadsheet since buying the car wherein I keep, inter alia, a log of the car's mileage at every fill-up. (I always fill to the brim). Real consumption, as measured through my spreadsheet, will always be more than that calculated by the trip computer. Typically around 10% out. So the car's trip might suggest 28 mpg, but the true calculations will be around 25.5 mpg.