In the past, cars, especially American cars were proud of their high displacement 8-cylinder muscle cars, but since the gas crisis hit and gas prices soared sky high, people began wanting more fuel efficient cars, and that led to the boom of 4-cylinder Japanese compact cars. And now with the environment and efficiency in mind, 3-cylinder cars are on the rise.
Why 4, 6, 8 cylinders?
Cylinders in car engines were almost always an even number, mainly because of balancing. With an even amount of cylinders, the other cylinder is used to balance out the force of the other cylinder moving (assuming even firing interval), so 4, 6, 8 or even 10 and 12 cylinder engines were amazingly smooth since there is always another cylinder balancing out the motion of one cylinder.
But 3, 5 cylinder engines do exist
5 cylinder engines were existent and quite popular, but they were still, more “shaky” compared to even-cylinder engines and quite a niche product. But now with better technology and the need for sustaining the environment, engines now are aiming for small displacements that can produce sufficient amounts of power, with those more powerful engines matching high displacement engines of the past.
3-cylinder small displacement engines were scarce back then, but are getting more and more popular, being equipped in tiny fuel efficient city cars (such as the Perodua Axia) all the way up to high performance sports cars (such as the Toyota GR Yaris), making headlines and dominating the market.
Why they are getting more popular
Much research has been put into it making 3-cylinders better, such as better balancing shafts to even out the forces and better vibration damping from engine mounts all the way to the steering column of the car, the end user is less likely to feel the downsides of a 3-cylinder engine in the cabin, and even going unnoticeable in the engine bay.
3-cylinders also have their good points, since they have 1 less cylinder than most 4-cylinders, there is less friction in the engine, and they are also more fuel-efficient due to their smaller capacity. Since their overall engine size is also smaller, this leads to manufacturers able to increase the cabin size, or even produce smaller cars.
Which you prefer is still up to you, the smoothness of a 4-cylinder or the efficiency of a 3-cylinder. But with hybrid and electric cars on the rise, we may see combustion engines getting smaller and smaller, and maybe being replaced by electric motors in the future.