Currently reading: Merc ponders 3-cylinder engines
Firm hesitates over whether to use three- or four-cylinder units in next-gen engines

Mercedes bosses are poised to decide whether the firm’s next-generation of downsized engines will be three- or four-cylinder units, according to a senior company source.

The new engines – sized between 1.4- and 1.6-litres will be used in both the next-generation A/B-class replacement and the C-class range.

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 V6 unit) "was relatively expensive to optimise".

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-pot layout.

As well as extra sound deadening, more sophisticated engine mounts and selective stiffening for the bodyshell 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.

Hilton Holloway

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eseaton 14 December 2009

Re: Merc ponders 3-cylinder engines

I always thought that engines configured in multiples of 3 cylinders were the optimum for smoothness in an engine?

artill 14 December 2009

Re: Merc ponders 3-cylinder engines

The 3 cylinder engines i have experienced have varied hugely. The engine in a 107 is very enthusiastic, but not smooth enough for a Merc. The original Insight was better, but used the electric motor to pulce in between strokes to smooth out the power delivery. Very clever, but not much use for Mercedes as i doubt they will be offing a hybrid any time soon at this end of the market.

However the 3 cylinder engines in the Polo and Fabia are nasty, especially the diesel. Maybe its because they are bigger, but what ever the reason, a 4 cylinder car would be a better bet than end up with something like that.

Uncle Mellow 14 December 2009

Re: Merc ponders 3-cylinder engines

TegTypeR wrote:
Would be interesting to see what could actually be done with the rotary engine and some decent development money.

There are other types of rotary engines which might be more effective if enough money was spent on development.

The only 3-cylinder I have driven is a VW one (in a Seat) and I had to look very carefully before deciding it was safe to put petrol in the tank.