Three-cylinder engines were popular with Japanese automakers back in the 1980s and 1990s, as a way of reducing weight and fuel consumption in smaller vehicles.

Now, they're making a resurgence, as low weight and improved efficiency are once again at the forefront of automakers' development tasks.

German automaker Daimler is now looking into three-cylinder engines for use in a range of small hybrid vehicles, reports Automotive News Europe.

The company has long equipped its Smart Fortwo city car with three-cylinder engines, but now sees them as a necessary factor in hybrid powertrains, where size issues make larger engines difficult to package.

Mercedes-Benz recently dismissed three-cylinder power units for its larger, rear-wheel drive vehicles on refinement grounds--the offbeat thrum of the typical three-cylinder engine must be controlled with balancer shafts, adding weight and impacting economy on larger vehicles.

Since Mercedes' larger vehicles are already designed to accept fairly large engines, hybrid vehicles with four cylinders don't present much of a packaging issue.

But Mercedes' head of powertrain development, Bernhard Heil, says the small size of a three-cylinder block means more space for fitting hybrid components like motors and controllers, making them an attractive option.

Three-cylinder engines on their own are already attractive in smaller vehicles, particularly in Europe, where their low internal friction and light weight make them idea for fuel-sipping small cars. In the U.S, 3-pot engines are offered in the Smart, Ford's Fiesta 1.0 Ecoboost and the Mitsubishi Mirage.

Daimler has co-developed a range of three-cylinder engines with French automaker Renault, whose new Twingo small car shares several components with Smart and its next generation of Fortwo and Forfour minicars. Those vehicles offer both turbocharged and non-turbo three-cylinder gasoline engines, all under a liter in capacity.

Mercedes' front-wheel drive platform, used under the A-Class, CLA-Class and B-Class--as well as the new GLA crossover--could all receive three-cylinder engines in the future--competing with BMW's new three-cylinder MINI Cooper and 2 Series Active Tourer.

Unfortunately, these engines are unlikely to make it to the U.S, where even four-cylinder engines are regarded with suspicion in upscale cars like Mercedes and BMWs.

Would you drive a three-cylinder Benz? Leave your thoughts in the comments section below.


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