Daimler Reportedly Close to Decision on 3-Cylinder Engines for Mercedes-Benz

Daimler Reportedly Close to Decision on 3-Cylinder Engines for Mercedes-Benz

By Scott Doggett December 17, 2009

Daimler executives are close to deciding whether to manufacture fuel-efficient 3-cylinder engines for several of its Mercedes-Benz models, the British publication Autocar announced today.

As we reported Wednesday, those same executives have just decided to put a four-cylinder diesel engine in Mercedes' flagship S-Class models starting next year.

The 3-cylinder engines - sized between 1.4- and 1.6-liters - would be used in both the next-generation A/B-class replacement and the C-class range if Daimler decides to embrace the 3-pot, Autocar said.

Although BMW has already committed itself to using a thee-cylinder engine in the next-generation 3-series, Mercedes bosses are hesitating to follow because of what they say are the extra costs and complexity involved.

One senior source told Autocar that using a three-cylinder engine (most likely engineered as half of Mercedes V-6 unit) "was relatively expensive to optimize."

This means that extra, potentially costly, measures had to be employed with the to reduce the noise, vibration and harshness that is typical of a three-cylinder layout.

As well as extra sound deadening, more sophisticated engine mounts and selective stiffening for the body shell would all be needed, adding to the costs of what would be entry-level models for the brand.

According to the source, the cheaper alternative is for Mercedes to look for a partner who could supply a more conventional four-cylinder unit, which Mercedes could then modify with its own direct injection and turbocharger.

Scott Doggett:  is an AutoObserver.com Associate Editor.