2016 Lexus RX: Creating the Fourth Generation

Gary S. Vasilash

The Lexus RX crossover has been enormously popular since it went on sale in March 1998. So when chief engineer Takayuki Katsuda had to develop the fourth generation vehicle, he had quite a challenge. Especially as he had to best the third generation—for which he’d also been the chief engineer.

Here’s a heck of a problem to have: For years, Lexus has been awarded for its high levels of quality. It is the same sort of quality, durability and reliability that parent Toyota has been associated with. But like Toyota, Lexus vehicles have been criticized. The knock on Toyota is that the vehicles are too “appliance-like.” For Lexus, it’s that the vehicles aren’t “emotional” enough. (Of course, this criticism generally comes from people who don’t actually worry about their cars starting every day or who can afford a second—or third—car to supplement the finicky-but-expressive one they have in the garage.)

Year after year, sales leadership notwithstanding, Lexus seemed to lack the street cred that was afforded to the German luxury OEMs for their design (even though one of the three has spent the past several years being consistently inconsistent in its design approach).

Akio Toyoda, president and CEO of Toyota Motor Corp., apparently has had enough. He is pushing the entire organization to come up 
with more expressive designs. While arguably the Toyota Production System has emphasized manufacturing at the price of design (e.g., minimizing the number of hits that a part can have in order to minimize takt time), Takayuki Katsuda, chief engineer of the 2016 Lexus RX 350 and RX 450h, explains that this is no longer the case.

And just how committed Toyoda is regarding having a more expressive design was something that Katsuda and his team learned first-hand. About a month before design freeze, Toyoda looked at the final design clay and wasn’t satisfied, Katsuda recalls. He thought that the curvatures weren’t as fully formed and the edges weren’t as sharp as they should be in order to achieve what he’d seen in the sketches. While it was evident that making the changes would have an effect on the manufacturing and stamping processes, Katsuda says that Toyoda told him, “Challenge engineering.”

And so they set to it. “We had to make changes to the vehicle even though we felt that we had done everything we could. But we were very motivated by his drive to work even harder. And it helped create a feeling of ‘One Team.’”

In Katsuda’s case, the fourth-generation RX was particularly challenging. Katsuda, who joined Toyota in 1985, having received a degree in aeronautical engineering (so presumably he knows more than a little something about edges and curves), worked on a number of European models before getting his first chief engineer assignment . . . on the third generation RX.

“That made working on the fourth generation more difficult,” he says. “I had to reflect on the current model and identify points that needed to be improved. I had to criticize all the work that I had done for the last model. It was not easy.”

He admits, “There is an advantage to knowing the car in depth so as to make whatever changes that needed to be made.”

Still: “It is harder to criticize your own work than when someone else has developed a vehicle and you’re picking it up.”

That said, they went to work and engineered a vehicle that will be built in two manufacturing facilities that are pretty much a globe apart, Toyota Motor Manufacturing Canada and Toyota Motor Kyushu in Japan. The vehicles available in North America are being produced in the award-winning Canadian plant (e.g., it was the J.D. Power & Associates Platinum Plant Quality Award winner in 2011 and 2014).

Katsuda: “I started with the mission to exceed the RX while still being the RX. I wanted it to be familiar, but with a more engaging driving experience, styling and luxury.”

So let’s walk through those points.

As for familiarity, as for their theme “Exceed the RX while still being an RX” (realize that they want to keep their customers while expanding the base, which goes to making a vehicle that would appeal more to men), one of the fundamentals is that the fourth generation vehicle is approximately the same size as the third.

It is 192.5 in. long, which is up 4.7 in. It is 74.6 in. wide, up 0.4 in. It is 67.7 in. high, a 1.4 in. increase. The wheelbase is 109.8 in., up 1.9 in.

Although both vehicles have the same interior volume—139.7-ft3—they’ve carved out space on the interior of the car for more passenger room, as in front and rear legroom of 44.1 in. and 38.0 in., respectively, versus 43.1 in. and 36.8 in., and front and rear headroom of 39.4 in. and 39.1 in. versus 39.1 in. and 37.7 in. 

While the overall form of the vehicle is the same, with a similar profile to the previous generation, Katsuda says: “The exterior designers created bold and outstanding proportions without minimizing appeal.”

“There is an upscale look at a single glance.”

The design theme was “Seductive Strength.” The increase in wheel-base means the wheels are pushed fore and aft; the A-pillars are pulled back, and the C-pillars are slanted more, and through the use of black-out trim in the C-pillar area, the roof appears to be floating. The spindle grille in front has a chrome-plated border. There are standard Bi-LED headlamps with an L-shaped LED daytime running light. (There are triple-beam LED headlamps, consisting of multiple, individual low- and high-beam LED elements in a uniquely shaped lens available.)

From a structural standpoint, the body-in-white makes extensive use of hot-stamped and other high-tensile strength steels. The ridge line of the cowl between the front suspension towers is straightened, thereby providing increased lateral rigidity; the cross member behind the cowl is extended, joining with the front pillars via the front pillar gussets, helping assure high joint rigidity. The side member outer reinforcement is joined with an annular frame construction process, helping improve body joint rigidity.

Lexus began using adhesive bonding on the 2013 LS sedan, and this is continued on the 2016 RX. Not only is the number of conventional spot welds increased (particularly around the rear hatch opening), but laser screw welding (a scanning-type processes that allows the generation of one-sided spots to be generated and provides the ability to weld mixed materials, as well as multiple sheets) is used to supplement the traditional spot welds to minimize cross sectional deformation.

While the vehicle is essentially steel, there are an aluminum hood and an aluminum hatch.

As for the driving experience, there is a MacPherson strut front suspension. They’ve increased the diameter of the front stabilizer bar from 26 mm to 28.6 mm to improve front roll rigidity; so as not to have a significant mass penalty, the new bar is hollow, with a 7.5-mm wall thickness, not solid like the previous generation. There is a double-wishbone rear suspension.

The RX has an electric power steering system. The angle of the steering column was lowered by 2° and the front seat lowered by 0.75 in. with the objective of providing a “sportier” driving position. There are disc brakes all around. There is an automatic brake hold function that controls the hydraulic pressure in the brake lines for each of the wheels; it is activated via pushing a switch; it is cancelled by stepping on the accelerator.

The RX 350 is powered by a 3.5-liter, DOHC, direct-injection Atkinson cycle V6 that produces 295 hp and 267 lb-ft of torque. Though the “VVT-iW” system, which both advances and retards intake cam timing as needed, the engine will switch between Otto and Atkinson cycles, with the purpose of improving fuel economy. The transmission is an electronically controlled eight-speed. The vehicle is available with a rear differential with an integrated, electronically controlled coupling that provides on-demand AWD capability.   

The hybrid version of the vehicle, the RX 450h, has a 259-hp 3.5-liter DOHC, direct-injected V6; with the hybrid motors, the total system output is 308 hp. Because this is a vehicle that offers AWD, in addition to the E-CVT transaxle in the front of the vehicle with two motor generators, there is a unit available, a rear transaxle with an electric drive motor that provides a maximum output of 67 hp. There is a nickel-metal hydride battery pack that is mounted under the rear seat.

The 2016 RX is available with a safety system that includes all-speed dynamic radar cruise control; a pre-collision system with pedestrian detection (it uses millimeter wave radar for determining the closing rate with the object ahead; it uses both the radar sensor and a monocular camera for pedestrian detection); lane departure alert (using the camera and radar); lane keeping assist (also radar and camera) that works when the dynamic radar cruise control is on to keep the car centered in its lane; intelligent high-beam headlamps (that use the camera and ECU that are used for the lane departure alert to minimize the number of components) that stay in high-beam until the headlamps from an on-coming vehicle are detected; blind-spot monitor and rear cross-traffic alert (both of which use the same radar mounted in the rear quarter panels); sway warning that alerts the driver that lane drift (possibly caused by drowsiness) is occurring; backup camera with dynamic guidelines; a panoramic view monitor that combines images from the camera mounted on the front, sides and rear of the vehicle; and a parking assist system that’s based on four ultrasonic sensors (four in the front; four in the rear).

Since it first came on the market in 1998, when Lexus was a U.S.-only company, up until today, when its footprint is global (it may be interesting to note that the Lexus brand didn’t go to Japan until 2005), there have been more than two million vehicles sold.

Which probably plays a large role in Katsuda’s thinking, “Exceed the RX while still being the RX.”