3/1/2003 | 11 MINUTE READ

Considering Sienna - 53,000 Miles in the Making

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An oft-cited phrase used to describe the development of vehicles nowadays is along the lines of “We designed it from the inside out.”


Facebook Share Icon LinkedIn Share Icon Twitter Share Icon Share by EMail icon Print Icon

An oft-cited phrase used to describe the development of vehicles nowadays is along the lines of “We designed it from the inside out.” The underlying acknowledgement of that statement is that people spend a considerable amount of time sitting in vehicles (e.g., long commutes that are exacerbated by gridlock and ever-lengthening rush hours; the recent propensity to drive somewhere rather than to fly). So in some significant ways, the inside is more important than the outside.

Although that particular phrase was not used during an explication of the development of the 2004 Toyota Sienna minivan, it is probably more authentically germane to that vehicle than to many others. John M. Jula, executive engineer/program manager, Development Planning & Operations, Toyota Technical Center U.S.A. (TTC; Ann Arbor, MI), notes that prior to being assigned to the Sienna program—for which he manages TTC’s engineering involvement (concept through launch), which includes managing internal engineering, coordinating supplier interfaces, and managing the overall project—he was general manager of something called “Engineering Design IV.” That meant that Jula concentrated on interiors. Instrument panels. Consoles. Restraints. And seats. Especially seats. Jula recalls that he was always developing clever folding seating mechanisms for various Toyota vehicles. And perhaps as one of those cases of “be careful of what you wish for,” Jula found himself pondering and being responsible for the 2004 Sienna seating. Indeed, one of the key differentiators of the Sienna is its seats.

Sienna seats were undoubtedly a concern of Yuji Yokoya, the Sienna chief engineer. He took the Toyota tenant of genchi-genbutsu to a whole new extreme. The tenant means “go, see and confirm.” The Sienna is a North American product. There is no Japanese equivalent. (When the Previa minivan, 1991-97, gave way to the first-generation Sienna, the Japanese and North American minivan programs diverged.) Yokoya decided that to really go, see and confirm what’s required for a minivan, he’d drive in every state in the U.S., every province in Canada, and every estado in Mexico. All in minivans. He covered some 53,000 miles in his trek in both Siennas and its competitors.

“My vision for Sienna was not the result of focus groups,” he observes. “It came from investing time on the road. . .behind the wheel.”

(That line ought to be kept in mind by any and all people who are involved in vehicle development programs—at least if they’re interested in achieving breakthroughs. Otherwise, stick with the focus groups.)

John Jula spent time sitting in the passenger seat to Yokoya during this journey. Jula is a big man, a robust man. Yokoya is comparatively diminutive. Clearly, there would be a concern vis-à-vis the seats after all of the hours on the road.

As the minivan as a class of vehicles is essentially one designed for families, the need to have an economical product (or at least one with a competitive price point) is essential. With the increased number of vehicles in the category, and with a well-regarded veteran like the Chrysler Town & Country and the highly demanded current-generation Honda Odyssey in the class, what Toyota would do to create a new Sienna was of some concern within the company. Jula says that during the development process for what they intended to be “the benchmark American minivan,” affordability presented the primary challenge.

Although “affordability” is sometimes code for “decontenting” (or at least the rationale for doing that), so far as they were concerned, that couldn’t be the case if they were, in fact, to create what could be considered to be a new standard in the category. Jula explains that he and his colleagues were working toward “setting a new standard in product quality, content and performance.” Yet there was that issue of cost: You can more readily achieve those things by simply adding expense, but that was not to be. So they concluded that they would need to find “new engineering efficiencies.” They set about on a program that, as he puts it, meant “rethinking and refining the entire development and manufacturing process.” The goal was to reduce costs without sacrificing the quality, content and performance.

And an important aspect was the seats. “Nowhere were we more indulgent with our budget than in the seat design,” Jula says. (Before joining TTC in 1996, Jula was director of Engineering-Interiors at Johnson Controls, where he worked on programs including the interior development for the Mercedes SUV.) Amplifying that, he remarks, “The Sienna seat-set was one of a handful of critical features where we said, ‘Damn the cost, let’s make it the best we can—and find a way to offset the extravagance along the way.’”

So how did they realize these offsets?

For one thing, there’s the reengineering of the sliding doors. In the previous-generation Sienna, the rear sliding door track assembly was positioned in the middle of the rear quarter panel. In the new Sienna, the rear track for the sliding doors (dual power sliding doors are standard on two of the four trim levels: the XLE and XLE Limited; on the CE and LE models, the dual doors are moved manually) is located along the bottom of the rear-quarter window. In addition to which, in the previous generation, the power for the sliding door uses contact terminals on the B-pillar and the doors. Now there’s a continuous power supply that’s provided by a flexible harness routed around the door opening. All of which means that there are fewer parts, reduced tooling costs, and simplified and faster assembly. Which results in reduced costs. (The location of the rear-track assembly on the ’04 Sienna looks significantly better than on the ’03—because you don’t notice it unless you’re looking for it.)

Another way costs were reduced was through the off-line processing of the Sienna headliner. Realize that this is a sizeable vehicle (e.g., wheelbase is 119.3 in.; overall length is 200 in.; overall width is 77.4 in.). One of the goals was to have plenty of interior volume: the total passenger volume is as much as 177.4 ft3 (seven passenger version); the total cargo volume is 148.9 ft3. Which is to say that the headliner is a large piece of material that needs to be handled in the Toyota Motor Manufacturing, Indiana (TMMI), plant, where it is built on the same line as the Toyota Sequoia SUV (here’s an interesting fact: the Sienna is unibody architecture; the Sequoia is body-on-frame). Not only is the headliner large, but there is the issue of complexity. For example, there are side-curtain airbags, a roof-mounted DVD system, air ducts, and wiring harnesses that are factors in the headliner assembly. So, instead of dealing with the headliner on line, which is the traditional way of doing it, the headliner assembly is done off-line, on a bench. Once everything is in place, the headliner is installed. Jula explains that what this means is that, “Adhesives have more time to set-up; final fit-and-finish is improved; total assembly time is reduced; worker fatigue and incidence of injury are reduced; and costs are reduced. The bottom line: We get a better headliner for less money.”

And the money can be spent elsewhere. Such as on the seats.

But before getting to the seats, it is worth noting that there was a significant deployment of digital assembly prior to any physical assembly. Even before there were any physical parts. In fact, Jula says that because the goal was zero engineering changes after the production drawings were realized, not only was there extensive cross-functional engineering during the program, but the vehicle was essentially “assembled” in digital form before prototype parts were produced. (For those counting: it was a 22-month program.) What the digital processing meant, in part:

  • Fewer costs associated with the engineering changes during product development (it’s cheaper to change digits than physical entities)
  • Reduced prototype tooling costs (some parts went straight to production tooling without any prototype tooling—this was not only made possible by the digital Delmia software, but also physical rapid prototyping, with, for example, a Quantum fused deposition molding machine from Stratasys for such things as modeling the all-important cup holders, of which there are 10 in the Sienna)
  • Improved manufacturability (assuring not only that the parts could go together, but that they could be reliability put together by workers under ergonomically correct conditions).

All of which meant time and money were saved.

So, to the seats.

Jula: “The level of comfort and convenience provided by car seats can be gauged on a spectrum that ranges from ‘showroom’ at the bottom to ‘long term’ at the top. Sienna seats are at the top of the chart. They were designed for maximum comfort and convenience for a wide variety of body sizes and shapes over an extended period of time.”

When you put as many miles in vehicles as the Sienna development people did, you can be sure that they know something about comfort and convenience with regard to the seating.

While how well one feels while sitting in a seat is certainly a subjective thing, there is something more about the seats beyond the comfort factor. This relates to Jula’s aforementioned design of folding mechanisms. The Sienna can be configured as a seven- (standard) or eight-passenger vehicle (with two people in the front, two or three in the middle row, and three in the third row). And within those categories, it is possible to configure the seats a total of 17 different ways. The changes really begin in the second row where on the seven-passenger version it is possible to move the captains chairs so that there is (a) an aisle in the middle for access to the third row (or to fit the moveable console from between the driver and passenger back) or (b) to form a partial bench on the left side of the vehicle. It should be noted that this seat maneuvering is rather simple to do. In the eight-passenger version, where there are three seats in the second row, the middle seat can be indexed forward nearly 13 in. so that it is partway between the driver’s and passenger’s seats (say if there is an infant that you want to have readier access to).

The third row seat folds flat into the floor—either entirely, or as a 60/40 split. In addition to which, the headrests can be pushed flush with the seat tops so that it isn’t necessary to remove them prior to folding the row down.

The ’04 Sienna is simply the kind of minivan that Toyota should have had all along. It is one that is well executed in a variety of ways, from having an appealing design with a sedan-like V-shape on the hood that has the badge in the center of its grille as the apex, a hood that is flanked by aero-style triangular headlamps. As mentioned, the sliding door mechanism is gone from the rear quarter, which provides a clean side to the vehicle that carries a character line from the center of the top grille (there are actually two, with an air dam grille at the bottom of the front fascia) back to the tail lamps.

It has the size that North American minivan owners have come to expect; it has the amenities (an array of storage compartments, cup holders, baggage hooks, etc.) that are certainly de rigueur. All models are equipped with ABS. The tailgate is powered. Front side and side curtain airbags, which cover all three rows, are standard on the XLE Limited and optional on the other grades. The XLE Limited features a sonar range-finding based park assist system. The navigation system that’s on the XLE and XLE Limited also provides parking assist because, when the vehicle is shifted into reverse, a video camera mounted in the back door is activated and the nav screen becomes its display. For the XLE Limited, there is a laser-based dynamic cruise control system that scans the horizon in front of the vehicle and can slow the Sienna in case another vehicle enters a preset perimeter via adjusting the electronic throttle control, brakes, and the transmission (starting with the throttle).

All trim levels have the same powertrain setup: a 3.3-liter V6 that provides 230 hp @ 5,600 rpm and 242 lb.-ft. of torque @ 3,600 rpm and a new five-speed automatic. Vehicle stability control (VSC) with traction control and brake assist is an available option. An all-wheel-drive version of the LE, XLE, and XLE Limited models will be available.

Both Yuji Yokoya and John Jula talk about the Sienna as a vehicle for children. In the words of Yokoya: “The parents and grandparents may own the minivan. But it’s the kids who rule it. It’s the kids who occupy the rear two-thirds of the vehicle. And it’s the kids who are the most critical—and the most appreciative of their environment. If I learned anything in my travels, it was the new Sienna would need kid appeal.” To be sure, the kids will appreciate the audio system and the optional DVD. They’ll probably be pleased with the room, even if they don’t really think about it.

But it is the parents and the grandparents who will have the preponderance of seat time. The adults will be most appreciative of the performance, of the versatility, of the amenities. They will be the ones who will be the most pleased. . . about the seats.


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