2012 MAZDA MAZDA3

The long-running automotive horsepower war might finally be grinding to a halt with a stalemate, at least in the compact car segment. Replacing power output one-upmanship is a new, much greener conflict over fuel economy. Among compacts, 40 mpg is the new target, one that the Mazda 3 has fallen woefully short of in the past. Not anymore.

For 2012, the Mazda 3 sedan and hatchback are available with Mazda's new "Skyactiv" powertrain components: a 2.0-liter four-cylinder engine paired to either a new six-speed manual or six-speed automatic transmission. Mazda's engineers essentially went through the internal combustion engine with a fine-toothed comb, looking at the myriad inherent inefficiencies and devising clever solutions to address them.

The result is a power plant that can hit that magic 40 mpg without "tricks" like adaptive front grille shutters or transmission programming that shifts the car into top gear at the earliest opportunity. Nor has the rise in fuel economy come at the expense of power. The new Skyactiv engine, which slots between the carryover 2.0-liter and 2.5-liter four-cylinder engines, boasts more power than the Hyundai Elantra and Chevy Cruze Eco -- two cars that also hit the 40 mpg threshold. Only the Ford Focus sports a better combination of power and fuel economy, but it only achieves 40 mpg highway with its Super Fuel Economy package.