Been a long time....: Cadillac redefines itself. (On Cars).

With the introduction of the SRX sport utility and the XLR roadster, Cadillac is proving that it is on the road to redefining itself in a more substantive way than just through the clever use of a Led Zeppelin song in its advertising. But just watch it move.

Nowadays, upscale crossover sport utilities are becoming the norm in premium showrooms. It all started in 1998 with the Lexus RX 300 (which has since become RX 330); it has been joined by a host of other vehicles. One of the characteristics of these SUVs is that they tend to be less truck-like in form than their body-on-frame counterparts. Sometimes it is a matter of their simply exhibiting smoother exterior lines. Or (think of the Volvo XC90) they look like, well, station wagons.

In the world of SUVs in general, General Motors is doing well, with an assortment of vehicles: everything from the Suzuki-based Chevy Tracker to the Suburban-based Cadillac Escalade. The Escalade is certainly a phenomenon, helping drive the age demographic down: according to Cadillac statistics, the average age of an Escalade buyer is 50, which is more than a decade younger than the average buyer of the brand.

With the burgeoning crossover SUV market, Cadillac executives set about to develop another variant off of the Sigma platform, the same platform that is used for the CTS, the vehicle that introduced the Art & Science design theme to the world with the pounding backbeat of John Bon ham on Led Zeppelin's 'Rock and Roll.' There is something to be said for not being first in this body-on-frame-integral luxury sport ute field. You're able to see what others have done, and learn from their delights and their demerits. It is clear that the people at Cadillac went to school on the competitors. They've engineered a vehicle that has a design and content quotient that will undoubtedly have the competitors going back to it as a touchstone.

The SRX has an evident familial relation to the CTS sedan. This is not merely a function of the designers taking the body panel direction that was originally inspired by the surfaces and angles of a stealth fighter. (There were some doubts about the CTS's market potential, yet in its first year it sold 7,876 more units than the 30,000 that it was expected to. That, you may think, is not all that big a number, until you calculate that it is 26% above the target.) There is more than a superficial relationship between the two vehicles. There is the aforementioned fact that they are both based on the GM Sigma platform. They are also both manufactured at the Lansing Grand River Assembly Plant, the 1.9-million-ft2 North American showcase for the GM Global Manufacturing System. In fact, both vehicles are produced on the same line.

What's a "Sigma"? One might assume that the CTS and the SRX are dimensionally the same size, given that they are based on the same platform. And one would be wrong. The SRX has a 116-in. wheelbase. It's 195-in, long (longer than either the Lexus RX 330 or the target, the BMW X5) and 72.6-in, wide. The CTS has a 113.4-in, wheelbase. It's 190.1-in, long and 70.2 in. wide. So what's the "Sigma platform" mean? Jim Taylor, vehicle line executive for Sigma, explains that there are at least a couple of ways to look at that. For one thing, there is a dimensional quotient. Although there is a disparity in size between the two existing vehicles, they are of an overall 'footprint" that can be accommodated by Lansing Grand River: the tooling and equipment can handle vehicles within a designated size. Taylor goes on to note that in addition to having common locating points, the Sigma vehicle process (i.e., are put together) in a like manner. For example, the engine modules attach the same way on the line whether it is a sedan or a sport ute.

Another aspect of the platform relates to what Taylor refers to as "the bits," the elements that are used to assemble a vehicle and consequently provide its character. He cites the all-aluminum suspension components that are used for Sigma vehicles. They are affordable in the price category that these vehicles retail at (e.g., the SRX starts at $37,995). And Sigma uses more ultra high-strength steel than other platforms in the GM system (e.g., the Epsilon platform that's used for the forthcoming Malibu); that steel is comparatively expensive.

The SRX is either a five- or seven-passenger vehicle, depending on whether the optional third row is included. Either way, it provides utility in the sense that if the seats are folded flat there is space for stuff--69.5-ft.sup.3]--and there is trailer-towing capability (a maximum of 1,000 or 3,500 lb., depending on options). It is a sporty sport utility vehicle in that it can be ordered with the 4.6-liter Northstar V8, which provides 320 hp 6,000 rpm and 315 lb-ft of torque at 4,400 rpm. (The base engine is a new 3.6-liter engine that also has variable valve timing; it produces 260 hp 6,500 rpm and 252 lb-ft of torque a 2,800 rpm.) Both engines are mated to five-speed automatics. The weight distribution of the rear-wheel drive vehicle (the SRX is also available with an all-wheel-drive setup) is approximately 50:50, so with the long wheelbase, the vehicle handles exceedingly well on the road... especially if the vehicle is ordered with the Magnetic Ride Control system, a Delphi-developed system that uses magn etic fluid for split-second suspension control (sensors measure the road surface in one-inch segments even when the vehicle is traveling at 60 mph and adjusts the stiffness of the suspension accordingly), a system that was first introduced on the Corvette... [second verse]

...which brings us to the second key introduction that Cadillac has, the XLR roadster. Which is a serious driver's car. While that claim may be greeted with the rolled eyes of "Oh, sure," it is worth knowing that the vehicle line executive for the XLR is Dave Hill. And it is worth noting that the XLR is being built at the GM Bowling Green Assembly Plant in Kentucky. If neither of those facts means anything to you, then try this: Corvette. Hill is the chief engineer for the Corvette. And the only other car being built at the Bowling Green plant is the 'Vette. The platform for the XLR doesn't have a Greek letter. It is simply called "GM Performance Cars." There's the XLR. And there's the Corvette. That's it.

One of the fundamentals that the two vehicles share is the structure. There are the hydroformed steel frame rails. The structural tunnel that runs down the center. The balsa-cored composite floors. There's the transmission (HydraMatic 5L50-E, electronically controlled five-speed automatic) location: mounted in the rear (the Northstar V8 with variable valve timing is under the hood, placed, for the first time for that engine, longitudinally--the Corvette, incidentally, doesn't use the 4.6-liter Northstar; it has one of two 5.7-liter engines under its hood). There's Magnetic Ride Control. There are the composite body panels.

An objective was to provide Cadillac with a vehicle that can compete with the Mercedes SL500, Lexus SC 430, and jaguar XK8, in terms of price ($76,200 MSRP), performance (0 to 60 mph: 5.8 seconds), and amenities (which we'll get to).

Keyless. One of the most notable clever characteristics of the XLR is its retractable hard top. The top, which is a combination of SMC (exterior), magnesium (frame) and aluminum (structures), folds up or down in 29 seconds. Push a button. Eight hydraulic cylinders are then actuated by an electric motor/pump system. But what's more interesting, perhaps, is the pushbutton start. You see, there's no key cylinder to turn to start (or stop) the engine. In fact, there are no key cylinders in the doors. There's no key cylinder for the trunk. Rather, there is a key fob. Put it in a pocket or a purse. When the fob is within one meter of the vehicle, then touch pads can be used to open the doors or trunk. And a button on the dash is used to start the vehicle.

There are no conventional door handles on the car designed by Tom Peters ("I like to describe this vehicle as a bow and arrow being drawn back, with a lot of tension and direction to it. Its form is stretched taught, very lean and muscular. The design projects chiseled form and pleasing style, but it also achieves all of those functional elements that are required for a world-class roadster.") Rather, there are molded-in pockets. Inside the pockets there are the touch pads. The design of those pockets, Dave Leone, XLR chief engineer, explains, led to a material modification. Like the Corvette, the body panels for the XLR are mainly SMC. (Compared with the Corvette, however, the SMC panels are thicker: 3 mm rather than 2.25 to 2.5 mm. Why? They're seeking a higher-quality surface finish for the XLR, and thicker is better.)

To make the rear quarter panels, an R-RIM material is used. That's because, Leone says, in order to get a sufficiently deep draw for the pockets, that material had to be used, as is also the case for the front fenders, where there are deep draws to contain the headlamps.

Although the XLR appears to consist of an assortment of flat panels, Leone points out: "There isn't a flat panel on it. Every panel has curvature." Care in processing those panels is utmost. He points out that when the panels are formed, they are removed with mechanical lifters rather than by hand: "If you're not careful when removing SMC parts from the tools, you can create microcracks in the parts. The microcracks manifest themselves in out-gassing in the paint shop in little pops, pits or blisters." Painting is a key concern. (In fact, one of the reasons why composite was selected for the XLR is because it shares the paint shop in the Bowling Green plant with the Corvette.) The parts are painted on fixtures. The fixtures are oriented so that the paint is applied when the primary surfaces are horizontal, thereby reducing the possibility of orange peel forming.

The array of amenities goes from the nine-speaker Bose audio system to heads-up display, from climate-controlled seats (a fan blows air over a thermo-electric ceramic disc to heat or cool the seat) to adaptive cruise control.

Mark LaNeve, Cadillac general manager, calls the XLR a "halo vehicle" for Cadillac. The metaphor may be somewhat apt. "Bat out of hell," however, comes to mind when you step on the throttle.