The latest Crown offers four different body types. This article shines the spotlight on the test drivers and engineers behind the fourth, the Crown Estate, and the 30 rejections that led to ever-better carmaking.
The 16th generation Crown comes in four different body types. Each model’s developers were committed to pursuing the core elements of “Crownness” (quietness, comfort, and quality) that have defined the driving experience over successive generations. At the same time, they imbued each vehicle with a distinct character unique to its body type.
A key role in creating the feel of a car is played by test drivers. To discover how they help shape the driving experience, Toyota Times spoke with the test drivers and engineers behind the development of each Crown series model. This time, we visited the genba responsible for the unique feel of the Estate.
Fatigue-free long drives
The Crown Estate is described as a fusion of wagon and SUV—a functional SUV for an active lifestyle.
“Of the four body types in the Crown series, this was the model where we most emphasized function,” explains Yuji Honma, who oversaw product planning for the Crossover, Sport, and Estate.
Honma
In terms of the scenarios we envisioned for our customers, we wanted to create a car that families or friends could load up with luggage for a long trip and would allow them to make the most of their destination.
Together with the development team, we strived to make sure long drives would be fun without being tiring.
As a test driver with the Advanced Technical Skills Institute Division, Tomoyuki Katayama provided development support for the entire Crown series. To achieve a fatigue-free experience on long drives, he says the team focused on straight-line stability.
Katayama
Just like the Crossover and Sport, for the Estate we also focused on delivering the Crown’s signature premium feel between zero and about 20 km/h.
On top of that, more than the other models, we specifically pursued straight-line stability—essentially, getting the car to drive as straight as possible.
From the outset, all Toyota vehicles are developed with good straight-line stability as an integral feature, giving customers confidence behind the wheel.
With the Estate, we aimed for a ride feel that further accentuates this aspect.
Honma
SUVs and other tall vehicles are more easily swayed by crosswinds, such as when passing a truck on the highway. In such cases, the driver will unconsciously correct the steering, but over long drives, this causes fatigue.
To prevent this, the team set out to create a car that was sturdy and stable, running straight and true as an arrow.
Aiming for fun to drive
At the same time, they also wanted to make the Estate fun to drive for those who like tight control.
Katayama
If you solely go after straight-line stability, you end up with a car that doesn’t turn as nicely as the driver would want, for example on winding roads.
Ride comfort, straight-line stability, and pleasant cornering. We needed to strike a balance between these aspects.
Atsushi Nishino (Vehicle Engineering Development Division), who contributed to the development of the Crossover and Estate as a test driver, was also keen to make sure that the car felt good when cornering.
Nishino
While ensuring it felt sturdy and stable, I didn’t want to detract from the driving enjoyment for discerning drivers.
Based on Katayama’s vision, we searched for the optimum ride feel by gradually adjusting the suspension spring rate, shock absorber damping, and stabilizer strength, along with electronic control components such as DRS (dynamic rear steering) and EPS (electric power steering).
Munekazu Ito, a fellow test driver at the Vehicle Engineering Development Division, recalls the struggle of EPS tuning.
Ito
Tuning the EPS on the heavier side makes it easier to produce a sturdy feel.
On the other hand, heavy steering inevitably makes drivers slower on the wheel. They then turn the steering faster to compensate, resulting in jerky movements.
To achieve a balance between these two aspects of performance, I worked with Katayama to repeatedly tweak our setup until we found the optimal tuning, where the steering feel fits perfectly with the car’s movements.
In this way, the development team harnessed the know-how gained from the Crossover and Sport to craft the feel of the Estate.
Yu Nishikawa, an engineer at the MS Platform Development Division, oversaw chassis design. He says the Crossover served as a benchmark for natural movement when cornering.
Nishikawa
Actually, getting the Estate to move like the Crossover was a challenge in itself, since it sits 25 mm higher, and the wagon body makes for a heavier rear.
One particular difficulty was achieving a turning motion that gives a natural roll feel during cornering. Doing that with suspension tuning alone inevitably brings a trade-off in terms of straight-line stability.
Instead, we began discussing how to achieve this balance through the entire vehicle, including the body shape.
Takuya Iwata is an engineer with the Vehicle Control Development Division and helped to develop the Estate’s handling stability and ride comfort. He says that, in adopting aerodynamic devices to achieve both straight-line stability and a natural roll feel, the team again drew on know-how from the Crossover and Sport.
Iwata
Many Toyota cars employ fin shapes in parts such as the side mirror base or rear combination lights to improve straight-line stability.
In this case, however, the design team had asked us to avoid changing aesthetic parts such as the rear combination lamp for an aerodynamic effect.
We therefore decided to add contoured airflow panels and fins to the car’s underbody, where they would not be visible.
The crab-walking car
Alongside the difficulty of balancing straight-line stability with a satisfying driving experience, the development team also ran into other formidable hurdles. Among them was calibrating the Rear Comfort mode.
In addition to the Sport and Comfort driving modes, the Estate offers a Rear Comfort mode focused on providing a pleasant ride in the back seats.
Specifically, the mode reduces swaying for rear-seat passengers by curbing vertical movement with AVS (electronic suspension control) and lateral rocking with DRS (rear-wheel steering).
According to Shinichiro Matsumiya, an MS Platform Development Division engineer who led chassis performance design and development for the Crown series, the Rear Comfort mode shines in situations such as highway lane changes or ramps.
Matsumiya
DRS is an electronic control system that improves maneuverability at low speeds by making the rear wheels counter steer and provides greater stability above 60 km/h by turning in the same direction as the front.
In Rear Comfort mode, the turning angle is increased considerably at high speeds. This means the car moves diagonally forward in a kind of crab walk, reducing lateral sway.
However, this can be an unpleasant sensation for the driver, which led to some harsh feedback from Katayama.
Katayama
When changing lanes on the highway, for example, normally the body rolls naturally from front to rear as the car turns, but initially in Rear Comfort mode the front and rear movements felt disjointed and rather unnatural.
I told them that if it makes the in the back more comfortable, there was no point creating a mode that exhausts the driver.
Some team members suggested scrapping it altogether. As Matsumiya tells, however, a lot of effort had already gone into developing the mode’s software, and he wanted to see it through to completion.
The commitment of Matsumiya and his fellow chassis designers was shared by Ito and Nishino—the model’s test drivers—who worked on calibration to somehow pull everything together.
Nishino
For our part, we sensed the potential of the Rear Comfort mode, so we spent time on the track determined to raise it to a level that would delight customers.
After taking our time with the calibration, we had Katayama get behind the wheel, and his feedback was, “You solved the turning, but now the straight-line stability is no good.” From there, we redid the calibration about 30 times before finally receiving approval.
Ultimately, they managed to reduce sway for a comfortable rear-seat experience, while retaining a natural feel for the driver.
Group Leader Ikuo Tachi, who supervises Ito and Nishino at the Vehicle Engineering Development Division, says that gaining Katayama’s approval on the calibration of a development vehicle had never taken this long before.
Tachi
Normally, we get the green light after one or two checks, but this time they really had to keep at it to see the calibration process through to the end.
I believe this is underpinned by the relationship of trust built up through past experience between our test drivers and Katayama’s inspection team at the Advanced Technical Skills Institute Division, as well as our shared sense of purpose in creating ever-better cars.
The engineers’ mission is to quantify the results achieved by Katayama and the other test drivers through the Estate’s development and harness this data in the next project.
Already, the expertise gained from developing the Sport and Estate models has been incorporated into an improved version of the Crossover.
This unflagging collaborative effort between test drivers and engineers will continue to spur the evolution of Toyota’s cars.