Looking beyond simple mpg figures, The Wall Street Journal looks at the total-cost-of-ownership for the most fuel-efficient cars.  The author factors in addition criteria such as selling price and calculates costs over a ten-year vehicle lifespan.  The MINI Cooper is one of the example cars in the article:

The Mini Cooper is one of a few truly cool small cars on the road. It handles well, feels quick, looks great—and gets 28 miles per gallon in city driving and 37 mpg on the highway, according to fuel economy estimates by the Environmental Protection Agency. Its average fuel economy rating in mixed driving is 32 mpg.

It also costs $18,800—a hefty sum for an economy car—and climbs much higher with optional equipment such as wheel, tire and stereo upgrades, and racing stripes or special paint. Without the extras, a Mini buyer is already paying $588 for each mile per gallon in that touted fuel economy rating, based on the 32 mpg average.

Of course the MINI buyer knows he or she is paying more than a Toyota Yaris or Nissan Versa buyer, the addition cost is buying quality and performance.  The simplistic cost calculations also miss important factors such as maintenance costs (free for the first three years for MINI owners) and resell value (high for the MINI).

Read the entire article Comparing Fuel Economies and Cost.