I drive a Co. car for work, and for my own travels I usually drive my Olds Alero. It's the 4 banger and gets over 30mph highway. My full size Chevy 4x4 only gets driven when I need to haul things. Even then, it gets 18mpg empty, 14 loaded well above maximum GVW.
ETA: Not all fuel efficient cars are pop cans waiting to be crushed. My GF got rear ended with my Olds, it completely folded up the front end of the Toyota sedan that hit her, smashed the battery, radiator, broke one of the ball joints, etc. The Toyo was going 40, wasn't paying attention, and made a quick attempt to stop but it was too late. Don't know how fast it was going at impact, but it had to be flatbedded. My Olds had two marks in the rear bumper cover from the license plate screws, and my tailpipe was bent downward, cracking the headpipe. My GF drove it home, and I got a new bumper cover and exhaust.