Two cylinders. A quarter of what many Americans consider the correct number, half of what you'll find in most economy cars. It's even a cylinder and over 100cc short of the smallest car engine on sale in the United States, the one liter (61 ci) three-pot found in the 2011 smart fortwo.

Despite this, it's just won International Engine of the Year 2011. The motor in question is Fiat's 875cc (53.4 ci) TwinAir, inline, two-cylinder turbocharged gasoline engine as found in the European market Fiat 500.

Other than the unusually low cylinder count, what makes the engine so special? The technology behind it, the fuel economy and the low emissions, that's what.

TwinAir is a development of Fiat Powertrain's MultiAir engine, as found in the 1.4-liter Fiat 500 available in the United States. It uses electro-hydraulic variable valve actuation to control air intake into the engine, rather than using a throttle valve. This optimises the amount of air drawn into the engine, allowing good torque at low engine revs, good power for the capacity and improved economy and emissions.

Use of a turbocharger gives the 875cc TwinAir an extra boost of power for 84bhp. A naturally aspirated version is due with 65bhp and a more powerful variant with 105bhp, more power than the 1.4-liter available in the U.S. Fuel consumption is 51mpg city, 65mpg highway.

A jury of 76 journalists and industry experts from 36 different countries placed the TwinAir unit not only at the top of the tree overall, but also awarded it wins for best engine below 1,000cc, Best New Engine 2011 and Best Green Engine 2011.

Will TwinAir make it to the States in the future? It remains to be seen. The upcoming 105bhp variant proves that small engines need not be underpowered (remember, the 500 isn't a large, heavy car) but we expect Fiat will wait to see how the 500 performs on the U.S. market before expanding the engine lineup.