Well I've only had cars that can be regarded as grossly inefficient around town. In chronological order...
1996 Ford Falcon (4.0L 1550kg family sedan)
1998 Ford Falcon XR8 (Normally 1600kg 5.0L V8. But this one was 5.7, with a supercharger)
1990 Subaru Legacy GT (2.0 turbo AWD wagon)
1994 Subaru Legacy 250T (2.5 AWD wagon. This one was auto)
1999 Ford Falcon (4.0L 1500kg sedan)
1998 Holden Commodore (Current car. 3.8L Auto sedan. 1600kg)
Rather oddly the 4.0 falcons and the Commodore are well suited to my driving. All are capable of 6.5l/100km on the highway (most of my miles) and normally get 8 (I have hills to deal with). But they get 15l/100km at best around town...
The next car (when I get back to NZ) is likely to be a little more sane. Ideally a diesel corolla. I'm thinking about building something like this
FuelVapor Technologies - fuel efficient vehicle automobile high mileage without the roof, but that's going to push my ability well past it's limit...