For the best mileage, the 2.5i manual is your best bet, rated at 20/27 mpg city/highway. Along with 1 mpg better highway mileage, the five-speed stick will help you get better acceleration out of the base horizontally opposed four-cylinder. The automatic has enough oomph for grocery-getting and other errands, but it quickly gets winded when pushed hard. The transmission could use a fifth gear; in many cases you can press the gas pedal halfway down without inducing a downshift, which doesn't help your passing confidence.

Outback 3.0 R Limited

On the other end of the spectrum is the 3.0 R Limited's normally aspirated 3.0-liter H-6 engine, which shaves another city mpg in exchange for ... not much. As the table shows, it brings a negligible horsepower increase and much lower torque — at higher rpm, where you don't want it. This option is the key to towing 3,000-pound trailers, rather than 2,700 pounds with the four-cylinder. If you're not planning to tow, I just don't see the point of this engine.