At 27 mpg city and 35 mpg highway, the base model with manual transmission is the greenest choice. Opting for the automatic cuts gas mileage to 25/30 mpg.
The Cooper S Countryman gains 60 horsepower but loses a few mpg in manual-transmission trim at 26/32 mpg. The automatic, however, improves to 25/32 mpg.
Adding all-wheel drive with the ALL4 model makes for the least-green Cooper S variant, but not by much: with the manual gearbox, it scores 25/31 mpg, while the automatic rates 23/30 mpg.