It's offered with a choice of conventional and unconventional powertrains, and for fans of driving efficiency, the 2011 Lincoln MKZ Hybrid is the green way to go, particularly since it's effectively a no-cost option.
The MKZ Hybrid's fuel economy of 41/36 mpg is identical to that of the near-identical Ford Fusion. According to Ford, that tops the Lexus HS 250h by 6 miles per gallon. The exceptional city number is due in part to the MKZ's ability to drive in EV mode up to 47 mph; the HS 250h only permits battery-alone driving up to 25 mph.
Lincoln has the green mentality down pat, all the way down to...flowers. The standard SmartGauge array of LCDs helps train drivers to cruise along more efficiently, by monitoring their consumption and battery usage. It translates those numbers into something everyone can understand--digitally rendered apple blossoms that add petals as drivers learn to conserve more fuel.
The other drivetrain choice in the MKZ is Ford's 3.5-liter V-6, coupled to a six-speed automatic. Its numbers aren't particularly draining, when compared to other V-6 engines, but fuel economy does drop to a low of 17/24 mpg when all-wheel drive is included.