Daimler AG’s Mercedes-Benz is rolling out an S-class sedan with a four-cylinder engine, a first in the model’s 60-year history as it vies with BMW AG and Audi for the “green” luxury driver.

A Mercedes-Benz USA spokesman said there are no plans to sell the model in the United States.

Mercedes is the first of the luxury carmakers to put such a small engine on its top-of-the-line model. To meet emissions standards and win environmentally aware customers, premium manufacturers are flaunting their environmental credentials. BMW has invested 1.2 billion euros in fuel-saving technology, while Mercedes nearly doubled its investment on “green” development to 1 billion euros this year.

Mercedes aims to maintain S class performance even with a downsized engine. The S250 CDI, which will arrive at dealers early next year, has a 2.2-liter diesel engine that has a peak power output of 204 hp and delivers maximum torque of 500 Newton meters at 1600 rpm.

Mercedes says the high torque at low engine speeds is a result of two-stage turbocharging and the engine’s torque figures are equal to a six-cylinder diesel.

With stop-start technology as standard, the S 250 CDI has fuel consumption of 5.7 liters per 100 km and CO2 emissions of 149 grams per km, making it the first car in the luxury segment to run on under 6 liters of fuel per 100 km and the first vehicle in its class to attain CO2 emissions below the 150 gram mark, Mercedes says.

AUTONEWS