Mercedes-Benz and BMW are both working on three-cylinder petrol engines that will be launched within five years.
All Mercedes up to and including the C-class will be available with a three-cylinder turbocharged unit, while BMW is developing cars to suit the quirky noise, vibration and harshness characteristics of three-pot engines.
“A three-cylinder engine in the C-class is quite conceivable,” said Daimler’s board member in charge of R&D, Dr Thomas Weber.
Daimler strategist Johannes Reisenrath went further. “Logically, if we go from eight to six cylinders with the same output to help economy, and we go from six to four cylinders, then four has to go somewhere too,” he said.
“Now we can do a 1.2-litre three-cylinder, so we can have 168bhp with a turbo, plus 150-185lb ft, which is enough to drive a mid-sized car like the C-class very well. It also has a six per cent fuel consumption benefit, and with 95g/km of CO2 fleet fuel consumption as a target, that’s an option we have to consider.
“We will have one on sale in the next four to five years.”Mercedes is working on making the three-cylinder cars as fast as the four-cylinder counterparts, too. Its research shows that customers want economical vehicles such as the three-cylinder model to be as quick as their current cars.
“From driving some of the earlier three-cylinder cars, they have a nice torque punch. We are much more advanced in turbocharging and gearboxes, so they will be even better next time,” said Reisenrath.
BMW sources have told Autocar that the next 1-series has been engineered to cope with the unique noise and vibration of a three-cylinder engine. BMW has had experience with three-cylinder units in its motorcycles, where reducing NVH is crucial.