You may not know this, but internal combustion engines are only efficient during a tiny part of their total operating range.

And that means when driving at lower speeds when demand on the car’s engine isn’t large, your car might not get the gas mileage you’d expect.

But Volkwagen’s latest 1.4 liter engine -- unveiled at this week’s 2012 Geneva Auto Show -- can make itself more efficient by deactivating its second and fourth cylinders when not required.

Cylinder deactivation isn’t a new thing. For some time, we’ve seen large capacity engines with 6 or more cylinders use deactivation technology to improve gas mileage when power demands are low. 

What makes Volkswagen’s 1.4 liter engine different however, is that it becomes the first four-cylinder, small-capacity engine to use the technology. 

Due to launch in the European-only 2013 Volkswagen Polo Blue GT, the 1.4 liter, 4-cylinder, turbocharged, direct-injected, cylinder deactivation engine promises an impressive 140 horsepower and a 0-60 time of under 8 seconds.

Even given its sporty heritage, the small Polo Blue GT -- a car that is slightly smaller in size than Volkswagen’s Golf -- gets up to 52 mpg when combined with VW’s seven-speed DSG dual-clutch transmission. 

When engine demand is low to medium, the engine operates as a two-cylinder engine, returning an impressive 16 mpg improvement in fuel economy over 4-cylinder operation at 31 mph in third or fourth gear. 

When the accelerator is pressed and engine demand raises, the two deactivated cylinders are reactivated in half a revolution.

In real world terms, that means instant power when it’s needed, and high gas mileage at other times. 

The U.S. won’t get to see the 2013 Volkswagen Polo Blue GT, or its eco-minded 1.4 liter engine just yet. 

But we’ve a feeling that won’t be the case for long, especially if Volkswagen can use the same technology in its 2.0 liter 4-cylinder engines currently found in the 2012 Volkswagen Golf and 2012 Volkswagen Beetle. 


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