When the existing fourth-generation Mazda 3 hatchback and sedan debuted in 2019, we lauded it for being smoother and quieter than the previous model. It also received a top safety pick award from the IIHS, making it among the safest family cars in the market. And Mazda did it without abandoning the nippy handling and driving feel that remains a hallmark of the "Zoom-Zoom" car brand.
It may not seem like it, but the fourth-gen Mazda 3 is an all-new model riding on an all-new platform and chassis setup. Perhaps its most significant and controversial change is the rear suspension. The outgoing third-gen Mazda 3 had a multi-link suspension in the rear, which was an independent architecture renowned for its fine-tuned balance of ride comfort and sporty handling. But for the fourth-gen model, Mazda engineers did a rethink and ditched the independent suspension for a torsion beam rear end.
Why is this significant, you ask? For an automaker that imbues all its cars with the "Jinba Ittai" (or "horse and rider as one") philosophy, wasn't it counterintuitive to ditch a sportier rear suspension for something as plebian as a torsion beam? In other words, how would the horse respond if it were given a donkey's hind legs?
There are reasons why Mercedes-Benz gave the W201 190 sedan the first multi-link rear suspension in a production car. It was compact, lightweight, and provided more grip — enough to trounce the BMW 3-Series in handling and cornering. Other carmakers have adopted multi-link suspension with three, four, or five-link architectures since then, mostly thanks to how it allows each tire to move in five directions.
The result is tighter handling, a comfier ride, and the freedom for suspension engineers to dial in their preferred geometries to make the car niftier, more comfortable, or something in between. But as with all things that sound excellent, there are drawbacks. For multi-link rear suspensions, there are more moving parts, which makes them complex and expensive to design and manufacture. And since there are more "links" and bushings to connect the suspension with the body and chassis, a multi-link adds more weight and can take up more space under the car.
On the other hand, torsion beams are simpler, lighter, and cost less to produce. Torsion beams typically have an H-shaped architecture, using one end with trailing arms to connect to the chassis and another to the wheels and axles. And since torsion beams are not officially classified as independent, they lose out in sporty handling and low-speed ride comfort.
Then again, torsion beams are cheaper to produce — hence why most inexpensive cars have them in the rear. The question remains: Why did Mazda choose torsion beams over multi-links for a car that gained a cult following for its agile, responsive driving feel?
Multi-link rear suspensions are great for sports cars or racing cars, but despite its handling attributes, the Mazda 3 is a family car. It's supposed to be a daily driver and not a hardcore track machine, so a simpler and lower-cost torsion beam is better for the purpose at hand. Plus, switching to a torsion beam solves the main issue that has plagued previous models of the Mazda 3, which was noise, vibration, and harshness (NVH) tuning.
Torsion beams don't have as many links or moving parts, making it easier to fine-tune the ride and handling while minimizing noise that typically stems from multi-link suspensions. And since torsion beams are simpler, more compact, and tend to sit lower under the vehicle, they free up more room in the trunk and rear quarters, which is evident with the new Mazda 3's more spacious cargo hold.
With the choice of forgoing proven multi-links for rear torsion beams, it's easy to criticize Mazda for skimping on costs in developing the fourth-gen Mazda 3. But it's not as if Mazda slapped an ordinary torsion beam and called it a day. The design is quite different from the rear suspension of the now-defunct Mazda CX-3 or Mazda 2, with a transverse beam that's wider in the center and stamped sections on the ends to mitigate rear wheel toe-in when cornering.
Apparently, the results speak for themselves. There's no denying the new Mazda 3 rides smoother and quieter than its predecessor, but whether it lost some of its sporty handling in the transition can only be judged if you take it on the racetrack. And you probably won't, since the 3 is a road car.