Mercedes-AMG may have the compact performance market sewn up with its successful 45 series powered by turbo four-cylinder engines, but its rival BMW M is having none of that. According to a report by CarAdvice, boss Frank van Meel said that a four-pot mill isn’t capable provide the kind of punch that it is satisfied with, adding that the venerable straight-six will remain a staple in its lineup.
“We are really happy with our six-cylinder [engines] because for BMW and BMW M that is our heritage engine. We started with six-cylinder in the M1 so it has a long history. BMW is a six-cylinder inline company and, for us, it’s an iconic engine,” he said.
Van Meel explained that a downsized, highly-boosted four-pot sacrifices low-end torque to deliver the headline power figures, as well as overall tractability. “I don’t see characteristics that I would like on an M car, on a small displacement turbocharged four-cylinder engine.
“I wouldn’t do a four-cylinder standalone turbocharged with high performance, because you always have the characteristic that if you want high performance you lose the low-end torque and you lose the overall driveability you want to have from the car,” he said.
Although van Meel wouldn’t discount the possibility of its application in a hybrid model – with electric motors supplementing the four-pot at low revs – such a technology brings its own set of challenges, not least of which being the weight of the batteries. As such, even a hybrid four-cylinder M car is some way off.
“Electrification would help because low-end torque is done with electric motors. On the other hand, you are putting a lot of weight into the car, so that answer is not so easy. To say ‘just do it,’ you lose the motorsport topic of power-to-weight ratio which is very important with overall weight.
“So, at the time being, it’s a dilemma – but we are working on that with our [BMW i] colleagues to have a look at the next generation of battery cells, regarding weight, power, density and range to find the right tipping point to say, ‘now it makes sense to go in that right direction.’ But today is not the right time,” van Meel said.
Although the company has already confirmed that hybrid M cars are on the way, van Meel said that the technology has yet to mature to the standard it needs to be at.
“With the current generation we see e-motors that are still not strong enough for M applications, and if you look at plug-in hybrids, it will add 200 to 300kg – which, for a car like an M3 or M4 with 1,500 kg, would put that completely out of balance and we can’t rebalance that towards a typical M philosophy.
“So, with [current] technology, we don’t see that [working], but I can’t tell you what the next steps with the BMW group will be,” he said.
Van Meel’s comments mean that there will likely be no M version of the next 1 Series, which will move to a front-wheel drive platform and hence will only have room for a maximum of four cylinders. The current rear-wheel drive model lineup is topped by the M140i, a halfway-house M Performance variant powered by a 340 hp 3.0 litre turbo straight-six.
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