Downsizing engines is a common theme at most carmakers these days, and has been for some time. Adding turbo to smaller cylinder counts yields similar performance to larger engines while saving fuel. But most of the talk has been limited to four- and six-cylinder engines--three cylinders have been pushed to the sidelines.

Why? In part because three-cylinders carry a bit of a stigma in the U.S., having been associated in the past with extreme discount economy cars, like the Geo Metro. Beyond the cheap-car stigma, however, three-cylinders are also seen as simply too small to deliver the power Americans expect from even the most ordinary car. But that's changing, thanks in part to new technology.

BMW, for instance, is expanding its TwinPower twin-scroll turbocharging system to three-cylinder engines, and plans to begin using them in a range of vehicles, especially its ultra-efficient i-branded models. Other carmakers including Volkswagen, Porsche, Ford, and possibly Mercedes-Benz are also working on or already have some form of turbocharged three-cylinder engine.

But can a three-pot gain acceptance in the wider market? If so, can it justify a spot in the luxury ranks? BMW thinks so, and even plans on putting a three-cylinder into its meat-and-potatoes 3-Series range at some point in the future. As yet, however, it's not a priority, Klaus Draeger, BMW's development chief, told Autocar.

When the three-cylinders do come to the 3-Series lineup, expect them to displace about 1.5 liters and generate as much as 160 horsepower. That's nothing to sniff at, especially in terms of specific output, but it's still a relatively tiny figure compared even to BMW's 2.0-liter TwinPower four-cylinder, which rates 240 horsepower at the crank.

The first BMW-built models to get the three-cylinder will be the upcoming front-drive i-branded models, the third-generation MINI, and the re-badged, sub-1-Series "new" 1-Series.

[Autocar]