Bring back the wagons
The last capable wagon, Buick Roadmaster of 1996, aka Chevy Caprice and Olds Cruiser, had a LT-1 engine. Basically same as the Corvette, and also had a highway rating of 26mpg, city was 17mpg. It could also out accellerate most cars on the road. I have a Crown Victoria (2003) rated at 25mpg, but I get 28mpg on long trips, the Roadmaster probably would too.
With the tow package you could tow up to 5000 lbs. Vehicle weight was about 4200 lbs.
The 2007 Tahoe weighs 5265 in 2wd form, and gets 22/16, better this year because of automatic cylinder shut-off at cruising speed. It can tow more: up to 7500 in 2wd, with a 3.73 axle ratio, which probably won't get the 22/16.
Anyway, the SUV's get such cruddy mileage because of their weight, but also because of their height. That tallness reduces the efficiency by about 20%. That's why I like the wagon, more like a car to drive, less likely to tip over too.
The only real wagon available now is the Dodge Magnum, it will tow 4000 lbs with the HEMI, but I have never seen one with the tow package. The dealer says they will just put the hitch on, but I want all the oil cooling, and 7 pin trailer plug wiring so I can put in an electric brake controller. The dealers would just rather sell you a truck or suv, which is fine, but personally I don't want to have that much heavier vehicle for all my driving.