2020 Mazda3: suspending disbelief

Hey there, time traveller!
This article was published 27/09/2019 (2514 days ago), so information in it may no longer be current.

One of the realities of automotive public relations is hosting an event where the manager of vehicle dynamics speaks eloquently to journalists about how the new suspension allows for stiffer springs without sacrificing ride quality, and then everybody jumps into the cars and drives them on nearly perfect roads.

That was our experience earlier this year in Sacramento, Calif., where Mazda hosted an event to show off the new Mazda3. The roads were outstanding: curvy, hilly and almost silken in their smoothness. Not a frost heave or pothole in sight.

We got to experience how well the new Mazda3 handles, and how the seemingly incongruous decision to abandon an independent rear suspension in favour of a torsion beam actually offers a surprising improvement in handling over the previous generation. Can’t say we noticed the cleaned-up inputs, however.

So when Mazda Canada popped two models — a sedan and a hatchback — into the press fleet and sent them to Manitoba, it was interesting to drive them on Winnipeg’s roads, which are far from optimal.

On Thomas Avenue in Elmwood, there are unpatched gouges almost every eight feet. Gouges that are patched were done poorly. Given its poor condition, it’s an excellent road. For testing suspensions, that is.

You do feel every little crevice, every little ravine. Considering Thomas Avenue is the location of the city’s East Yards, it’s ironic this road in particular is so bad. But what sets the Mazda3 apart, even with significantly stiffer springs, is how normal the ride is. It’s not the least bit harsh the way most stiffly sprung cars can be.

Dave Coleman, the manager of vehicle dynamics mentioned earlier, said Mazda spent considerable time studying the effect of bumps on vehicle occupants and found that on the previous Mazda3, hitting a bump not only caused occupants’ heads to rise, a slight deceleration on impact also caused them to move forward.

Engineers traced this to two bushings on the front suspension control arm: a softer lower bushing and a cylindrical upper bushing were transmitting deceleration forces to the cabin instead of absorbing them. Putting a stiffer bushing down low and a ball-joint style bushing up top means these deceleration forces are absorbed without adding upward force to the chassis.

“It can flex, but it can’t move up,” Coleman said.

“As we get these inputs cleaner and cleaner, we can make the suspension tuning stiffer and stiffer and still be comfortable.”

How they managed to get a torsion beam at the rear to work as well as or better than an independent is as surprising as the decision to go with a torsion beam in the first place: by reducing the number of bushings.

Reducing the number of bushings made the movement of the torsion beam more predictable and reduced the extent to which the rear wheels steer in reaction to movement in the suspension, something engineers call “compliance steering.” Mazda experimented with this concept deliberately in versions of the RX-7 sports car to provide a passive rear-steering system, but generally, having the rear wheels change direction in response to flexing in the suspension isn’t desirable.

Mazda, as has been its practice, rolled out two versions of the new Mazda3: a sedan, and a Sport or five-door. Typically, this means the really cool-looking one is the five-door while the sedan comes out looking frumpy. Not so here: the sedan may actually be prettier. On the Mazda3 Sport, one design feature could be a bit polarizing, and it’s how the rear fenders flare out. The sedan has no such feature: indeed, very few body pieces are shared between the two cars.

The sedan loses a bit of practicality, with a trunk lid where there’s still cargo space in the five-door. It’s not that much, however: sure, it means you can’t haul items quite as big, but in terms of smaller items that you shouldn’t leave unrestrained above the level of the rear seatbacks, not so much. It gains a bit of quiet, however, with the seatback and rear-window shelf providing a sort of seal between the cargo bay and passenger cabin.

Mazda makes available both styles of transmissions, and while I’d never pass up the chance to drive stick, Mazda’s work on developing its automatic means it’s fun to drive as well. The secret here, since Mazda doesn’t believe in eight, nine or even 10-speed transmissions, is in the engine, actually. Managing the torque curve has been key to achieving good fuel economy with six speeds and no engine start/stop feature.

All-wheel drive is available on both body styles, but the stick is just available in front-wheel drive. To get a stick in a higher trim level, you have to go to the Sport, where a six-speed manual is available on all trim levels.

kelly.taylor@freepress.mb.ca