Three-cylinder engines used to be the preserve of budget cars. They were light, economical and inexpensive. But most also tended to be tinny, wheezy and buzzy.
So when BMW Group announced a few years ago that it would be using three-cylinder power plants, it had on its hands a monumental task.
It had to come up with an engine that meets increasingly stringent emission standards (the primary reason for the downsize) and, at the same time, meets people's high expectations of a BMW engine.
From the looks of it, it has succeeded. The turbocharged 1.5-litre inline-three in the BMW i8 hybrid sports car puts on quite a convincing performance. It even sounds convincing, with the help of electronic acoustic amplifiers.
Together with an electric drivetrain, it helps the i8 achieve an unbelievably low consumption of 2.1 litres/100km.
The power plant is also found in the new 2-series mini-MPV, which will arrive here in the fourth quarter, not long after the i8.
You will not have to wait, though. The puny three-cylinder powers the new Mini Cooper (BMW owns Mini), which is already here.
The engine proves its mettle by being very punchy, sounding very throaty and faring not too shoddily in the economy department (about 7.5 litres/100km).
In fact, it suits the character of the Cooper quite well, with a refreshing youthful exuberence that is underscored by its free-revving nature.
Tap the throttle and the engine responds without a hint of hesitation. With peak torque of 220Nm arriving at 1,250pm, the Cooper does not exactly require high revs to thrive. But the tacho climbs easily anyway.
It goes past 4,000rpm with little effort and raises a wonderful ruckus along the way. Its note is surprisingly soulful and textured, with a metallic undertone that differentiates it from the 2-litre four- cylinder turbo found in the more powerful Cooper S.
It sounds good on its own, without the benefit of an artificial enhancer.
The three-cylinder Cooper does not feel drastically inferior when compared to the S, even though on paper, its performance is clearly a notch below.
It takes a pretty decent 7.8 seconds to reach 100kmh, compared with the impressive 6.7 the Cooper S clocks. It maxes out at 210kmh, versus its more accomplished sibling's 233kmh.
But on the road, the Cooper is more than adequately quick. And it offers a measure of agility and nimbleness that seems more relevant to everyday applications.
Whether hurtling from the lights, filling gaps in flowing traffic or pulling out of an acutely sharp corner, the three- cylinder Mini is just about flawless. And entertaining.
In fact, it seems a tinge more entertaining than the Cooper S, which is more muscular but a tad detached and aloof at the same time.
The Cooper screeches with carefree abandon, and at the slightest provocation. Wheelspins accompany hurried take-offs and tyre squeals follow hard cornering. Blend in the delightful roar of the engine as it works its way up the car's six-speed gearbox and you have an aural orgy that raises hair and clears pores.
In short, given a choice between this car and the more illustrious Cooper S, I am betting that most people will pick the former. Its smaller sticker price aside, it will be primarily because of its irrepressible inline-three.
Perhaps BMW should have adopted this engine configuration from the start. Back in the 1990s, Rover (which BMW once owned) actually proposed a three-cylinder engine for the new Mini.
But of course, turbo technology was not as sophisticated as it is today. And a normally-aspirated inline-three from Rover would most definitely have been tinny, wheezy and buzzy.
