Not so many years ago, a 1.2-liter engine would only have been found in the U.S. in the smallest and least impressive of subcompact cars.

It might have been a 3-cylinder, and certainly wouldn't have had even 100 horsepower.

But times change, and engines of that size will soon be found even in the smallest of Mercedes-Benz luxury cars.

DON'T MISS: 2014 Mercedes-Benz CLA 250: Gas Mileage Review Of Compact Luxury Sedan

The engines won't be seen until 2019 or later in North America, and then only in the CLA compact sedan and perhaps the GLA compact hatchback utility vehicle.

But as well-sourced correspondent Georg Kacher noted in the British magazine Autocar in May, Mercedes parent Daimler remains under increasing pressure to reduce carbon emissions and boost fuel economy in markets across the globe.

Introduced for the 2014 model year, the Mercedes-Benz CLA gave the German luxury maker an entry-level luxury offering originally priced just under $30,000.

2018 Mercedes-Benz CLA-Class

2018 Mercedes-Benz CLA-Class

The first front-wheel-drive Mercedes car sold in the U.S., it boosted the company's EPA fuel-economy ratings and let the rear-wheel-drive C Class move up in the lineup, away from its previous entry position.

Hot-rod AMG versions aside, the CLA and GLA are powered by a 208-hp 2.0-liter turbocharged inline-4 powering the front wheels mated to a 7-speed dual-clutch automated manual transmission. All-wheel drive is optional.

The report suggests the CLA's replacement could use 1.2-liter or 1.4-liter engines, again turbocharged. The next-generation car might be seen in the U.S. as a 2020 model.

READ THIS: 2015 Ford Focus 1.0L EcoBoost: Gas Mileage Review

It's not clear that even the 1.4-liter turbo four would come to North American markets, whose buyers tend to require quicker performance even from smaller cars than those in other regions.

But the idea of a 1.2-liter engine in a C-segment luxury vehicle (as compact cars are called in the industry) still remains a relatively recent innovation.           

The Ford Focus compact sedan is offered in North America with a 1.0-liter turbocharged 3-cylinder EcoBoost engine, but its sales are likely miniscule because it comes only with a 6-speed manual gearbox, a nonstarter for most U.S. buyers.

2018 Mercedes-Benz GLA, 2017 Detroit auto show

2018 Mercedes-Benz GLA, 2017 Detroit auto show

Engines of that size in compact cars are far more popular in Europe, where several countries base their annual registration fees on displacement or carbon emissions.

That offers an instant cost advantage for the smaller engines, but no state in the U.S. registers cars that way.

Even if the Trump government's EPA and NHTSA cut 2022 limits on carbon emissions and corporate average fuel-economy rules respectively, neither China nor the European Union show any signs of budging from increasingly stringent limits on vehicles' carbon emission limits.

CHECK OUT: VW suggests engine downsizing is done; emissions rules are the reason

That will require Daimler to make its smaller cars even more fuel-efficient than they are today.

Under fuel-economy ratings that were revised for 2017, this year's base Mercedes-Benz CLA 250 sedan is rated by the EPA at 23 mpg city, 32 mpg highway, and 27 mpg combined.

The Mercedes-Benz CLA sedan and GLA hatchback utility were jointly developed with Nissan's Infiniti unit, which uses the same underpinnings in its own Infiniti QX30 hatchback utility vehicle.


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