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EQUINOX: Executing the Theta Architecture in a Bigger Package

One of the faster-growing vehicle segments is that of the compact SUV. According to Chevy's Margaret Brooks, marketing director for the Equinox, it represented 7% of the U.S. market in 2003 and is on its way to 8.5% by '08. So Chevy is now in the game with the Equinox, its first "car-based" SUV.

The joint-venture manufacturing operation between General Motors and Suzuki Motor Corp., CAMI, in Ingersoll, Ontario, was in need of a vehicle as the Geo line has gone away and the small Tracker SUV went out of production. There are two lines in the plant. And one of them is now hard at it. It is building an SUV, this one for Chevrolet. Just as CAMI was looking for product, Chevy, which is undergoing a massive redo of its product lineup, was looking for a product that it could have at the entry level of SUVs.

The line in question has an annual volume of about 150,000. And the folks at Chevy hope to sell about 100,000 units of the Equinox. They may actually need to use more of that volume. That's because although it is nominally a "compact" SUV—one that's competitive with the Ford Escape, Jeep Liberty, Honda CR-V, Toyota RAV4, Hyundai Santa Fe, and Kia Sorento—it offers something that's sufficiently different from the rest of the pack: It's bigger.* And it provides some interesting interior packaging as a result of some clever engineering.

The '05 Equinox is based on the GM Theta architecture. Talking about it, Jerry Gillespie, vehicle line executive (VLE), International & Joint Venture Programs (IJVP), describes Theta as "a global set of components." He says that the engineering on that set is performed globally. Equinox is the second Theta product. The first is the Saturn VUE. Given Gillespie's title and his comment, chances are, Theta will have some variants outside of North America. One thing to keep in mind about this GM approach is that an "architecture" is also something that can take variant forms: while the Equinox is based on a body-frame-integral design, the VUE is a space frame. In the context of the Equinox product development, the sharing of the platform has meant that Mo Wazir, vehicle line director (VLD) for the Equinox, was able to take the knowledge that he'd gained from working on the Saturn VUE, for which he had been the vehicle line director (he got the Equinox position in April 2002), and put them to work in comparatively short order. (It's worth noting that Wazir is the VLD for Theta within IJVP.)

It has also meant sharing of components, which drives down costs, both from the standpoint of purchasing (i.e., greater volume buys) and from that of engineering (the "set of components" have been proven out, so when they can be applied without change, the investment is already made).

While there are, in practice, geometric and dimensional descriptions or limitations to an "architecture," it's not exactly that simple. For example, the overall length of the Equinox is 188.8 in. and the wheelbase is 112.5 in. By comparison, the VUE has a length of 181.3 in. and a wheelbase of 106.6 in. The vehicle was "stretched" between the B-pillar and the rear axle.

Which brings us back to the issue of interior space.

The vehicle has what is called the "Multi-Flex" rear seat. This is a bench seat. It has a 60/40 split. It has two recline positions. Nothing seemingly too flex about that. But the big difference is in the fact that the seat can slide fore and aft eight inches. Bob Reuter, vehicle chief engineer, IJVP, claims that the Equinox provides more rear legroom than a Mercedes S-Class. Given that the S430 stickers at about $75K and the Equinox starts at $20,995, just think of how smug Chevy owners might feel when they pull up next to a Merc in the lot of Costco.

So the seat can go back and forth. And it can be folded flat, as can the front passenger's seat (which is just like the front seat of the VUE—because it is). So, when it is necessary to carry, say, an eight-foot ladder, the Equinox can accommodate it.

Chevy aficionados may remark, "Ah ha! That's just like the seat in the Malibu Maxx." It can move fore and aft seven inches. Wazir says that this was simply a case of engineers working on both programs having the same idea at approximately the same time. And yes, he admits, the Maxx got out there a little early. But there is something very Malibu about one part of the Equinox: the steering wheel. The Equinox has the same steering wheel as the Malibu. But Wazir notes that although both vehicles have electric power-assisted steering rack and pinion steering, they use entirely different systems (e.g., the Equinox—and VUE—use a system from Koyo; Malibu's comes from Delphi.)

But the observation can be made that there is a GM strategy that means that Theta can borrow from other architectures, such as Epsilon (i.e., Malibu).

The Equinox comes with a standard 3.4-liter, overhead cam, 185-hp V6 engine, the GM 3400, a version of the GM Generation III 60-degree engine family. One interesting aspect of that engine—at least in the context of GM's global product development—is that it is being sourced from China. According to Robert Benedict, assistant chief engineer, HVV6 China Engine Programs, the GM Global Manufacturing System is in place in China at Shanghai General Motors (Pudong, Shanghai), as it is in other GM plants, so the Chinese engine is as good as an engine built in North America.

The Equinox also comes standard with an Aisin AF33-5 five speed automatic transmission. This is the same transmission that had been used for the VUE equipped with a six-cylinder engine—before the VUE switched to a Honda-supplied 3.5-liter, 250-hp six-cylinder engine and transmission package. Wazir says that a key reason why the Aisin transmission is used is because of its compact size: it has a 14-in. axial length.

So why the difference in the V6s? Why not offer the Honda engine/transmission package in the Equinox, as well. Wazir says one fundamental reason is value: the base MSRP for the V6 VUE is $22,405; the base MSRP for the Equinox is $20,995. And Chevrolet is meant to represent value.

The Equinox is available in either a two-wheel drive (front) or on-demand all-wheel-drive. When the all-wheel-drive system is engaged, about 33% of the power goes to the rear wheels. Because this system is automatic, and is engaged comparatively rarely, the estimated fuel economy numbers are the same for both versions: 19 city/25 highway.

* Equinox: Wheelbase: 112.5 in.; overall length: 188.8 in. Ford Escape: Wheelbase: 103.1 in.; overall length: 174.9 in. Jeep Liberty: Wheelbase: 104.3 in.; overall length: 174.4 in. Honda CR-V: Wheelbase: 103.1 in.; overall length: 178.6 in. Toyota RAV4: Wheelbase: 98 in.; overall length: 166.6 in. Hyundai Santa Fe: Wheelbase: 103.1 in.; overall length: 177.2 in. Kia Sorento: Wheelbase: 106.7 in.; overall length: 179.8 in.

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The Equinox is Chevy’s SUV that isn’t a body-on-frame—although one of the key characteristics of the Theta architecture that it is based on is that there are two main underbody rails that run continuously from front to rear, thereby providing a solid-structure for what can be considered a “car-based” SUV (even though the component set that makes up the Theta architecture, such as the MacPherson strut front suspension and the independent four-link rear suspension, are engineered for truck-like applications). The Equinox is designed to have a familial resemblance with its bigger brothers, the TrailBlazer and the Tahoe. Note the wrap-around hood design (Mo Wazir, vehicle line director: “That’s not easy to do.”) and the large clear-lensed headlamps, which have three parabolas, as do the tail lamps (although in that case, two of the three are red).