As promised earlier this year, Fiat has officially adorned their beloved 500 with a brand new engine option: the 2-cylinder TwinAir.

The 85 HP, turbocharged 0.9 liter engine reportedly has the performance characteristics of a much larger 1.4 liter, 16-valve engine, but it consumes about 30% less fuel—resulting in a fuel economy of 57 mpg as rated on the combined Euro cycle. If it were sold in the U.S. and rated on the EPA cycle, that number would likely drop to around 50 mpg.

Unfortunately for now, there are no plans to sell the 85 HP TwinAir engine as an option on any of the Fiat 500’s that are rumored to be reaching U.S. shores by the end of this year.

Okay, with a 0-60 mph time of about 11 seconds, a Fiat 500 equipped with the 2-cylinder TwinAir won’t be winning any drag races. But considering how tiny and miserly this engine is, 11 seconds doesn’t really seem all that bad either. And in an interesting bit of engineering, the TwinAir equipped 500’s will also have an “ECO” button to allow the driver to switch between getting maximum torque (and therefore performance) or getting maximum fuel economy. Not surprisingly, the diminutive engine features equally diminutive emissions. At just above 90 grams of carbon emitted per kilometer driven, the TwinAir is one of the least polluting combustion engines on the planet.

Fiat is also hinting that because of the incredibly reduced size of the TwinAir engine, it could be well suited to work alongside an electric motor in some kind of hybrid or plug-in hybrid configuration in future cars. The TwinAir will also be made available in a version that can run on compressed natural gas, making it an incredibly versatile platform.

Seems to me that the popular looks of the Fiat 500, combined with the green characteristics of the TwinAir combustion engine, wrapped up in an affordable package would sell incredibly well in the U.S… I just hope that Fiat and Chrysler also figure that one out.