Charles Darwin’s theory of evolution holds that all species of plants and animals developed from earlier life forms via the transmission of slight variations to successive generations. Those that survive this process are said to be best adapted to the environment. Or so the theory goes.

The automobile, and the auto industry, supposedly follow the same evolutionary rules. Products evolve, while new species and body styles arise out of the cross-pollination of traits from existing segments. Occasionally, recessive genes suppress the dominant ones and long-dormant body styles and vehicles reappear–which is as good an explanation for retro design as any yet put forward–and the adaptation process continues. Or so the theory goes.

Testing the theory as it applies to cars and trucks follows a practice akin to Darwin’s trip along the Pacific coast of South America aboard the H.M.S. Beagle. Thankfully, classifying vehicles by body style didn’t take the five years it took Darwin, though a week walking the North American International Auto Show seemed almost as long. Like Darwin, we use accepted classifications, adapting them to cover the hybrids that mimic the traits of one or more of the main body styles. Or so…well you get the idea.

Sports Tourers: The return of the station wagon Distinguishing Characteristics: Two doors or four, “one-box” or “two-box” shape, substantial presence, luxurious interior, front- or all-wheel drive. Natural Habitat: Upscale malls, country clubs, dirt roads leading to second homes. Comments: This may be the fastest growing segment in the industry today. It included the Chrysler Pacifica, Mercedes GST (Grand Sport Tourer), Infiniti’s FX-45, and the sporty Saab 93-X.

Chrysler Pacifica
When production Pacificas hit Chrysler dealers in 2003, they won’t have the full-length glass roof of the show car, but most everything else will be the same. The proportions combine elements of minivans, sedans, and SUVs, and creates a stance that is midway between each. A sharp peak–a design trademark for future Chryslers–runs down the center of the hood and adds stiffness to this panel. Raised rain gutters run along the roof to channel water rearward, and end at the liftgate roof spoiler. They replace the rubber “ditch” moldings seen on many vehicles today, and provide a raised, finished edge for the upper body side and roof panels. Chrysler sources say this design element will simplify assembly by making the joint between these sections less critical visually.

Mercedes Vision GST
Mercedes takes the “two-box” Sport Tourer body to near “one-box” proportions with the GST’s sweeping roof, and the integration of the A-pillar form into the hood. The Vision GST eliminates the B-pillar and relies on rear-hinged doors which open to 90º and give unobstructed entry into the back of the cabin. A large center console separates the interior into distinct right and left sections. Beneath it sits the driveshaft tunnel, which ties into the sills to recover some of the strength lost with the B-pillars. The doors are locked together via catches in the roof and sill area, and the roof is covered by a single sheet of electrochromic glass. In addition, transverse beams at the A-, C- and D-pillars connect the right and left halves of the roof to each other. For stiffness and style, the subtly curved body panels have sharp creases.

Infiniti FX45 Concept
Said by Nissan officials to be “very close” to the production vehicle’s final shape, the latest iteration of the FX-45 concept proved much brawnier looking than its 2001 predecessor. Of interest were the slim A-, B-, and C-pillars and nearly flush side glass. Unlike Audi, which makes its glass flush by piercing it with pins that run in hidden tracks, Infiniti wrapped the FX-45’s door frames over the edge of the side glass. This section is broad, but has very little offset from the glass surface, and offers a large clamping area to keep the glass in place at speed. The D-pillar is thicker at the top than at the bottom, joins the body along the large shoulder line, and provides a transition between the arched roofline and nearly vertical tailgate glass opening.

Saab 93X
Under the skin of the 93-X lies the chassis and drivetrain of the next Saab 93 sedan, and a look at how Saab will approach its expected SUV. The 93-X utilizes a two-door coupe body style that ends in a large, horizontally split hatch. The lower section drops down, and the load floor slides rearward to ease loading and unloading. The glass roof is split down the center by a large metal spine that attaches to the structure bridging the A- and C-pillars. This “halo” roof is a favorite of Saab design chief Michael Mauer, and likely to make it into production on future vehicles. The 93-X design team also used broad sill extensions to visually tie the satin finish front and rear wheel arch cladding together. In production, those pieces will be composite material, and snap-fit into channels. Different finishes and colors will delineate trim levels.

Crossovers: Recombinant DNA Distinguishing Characteristics: “Two-box” shape, high ground clearance, four-wheel drive, off-road capability. Fusion of SUV, minivan, and station wagon. Natural Habitat: School parking lots, strip malls, beaches, campgrounds, hip eateries. Comments: The SUV segment is mutating in a way that keeps the rugged attributes of traditional SUVs, and combines them with the softer “on-road” characteristics of traditional automobiles. It’s too early to say whether this species will replace the automobile, though crossovers are gaining greater access to auto company resources.

Acura RD-X
The B-pillars have been deleted to allow for easier ingress and egress, leaving thin C-pillars to do the support work. The tailgate is made out of two pieces of glass that slide apart, and–like the deep-draw front fenders–will never make it past the first production feasibility meeting. We’re certain a somewhat toned-down version of the RD-X will make it to the production floor in about 24 months, especially since Acura officials have publicly expressed interest in a small, sporty SUV.

VW Magellan
The Volkswagen Magellan blends SUV and station wagon body styles into a fluid whole. Rather than futuristic, the Magellan is understated and very manufacturable. The door panels are simpler than many VW already has in production, though the C-pillar has a sharp vertical line and subtle curve that could precipitate some overtime in the die shop. The rear quarter panel cut lines mimic the Golf’s, while those between the hood and front fender seem to be placed as much for manufacturing ease as for beauty, resulting in very narrow gaps. Production front lights will likely be more assembly tolerant, while the roof–made up of one massive panel that includes both the A- and D-pillars–is a configuration that would never make it to production in this form.

SUVs: Covering all the bases Distinguishing Characteristics: Four doors, “two-box” shape, plenty of ground clearance, all-wheel drive, at least some off-road capability Natural Habitat: Though carrying the cues of a vehicle designed for rugged duty, SUVs are most often found on paved roads and at soccer games. Comments: Despite being fragmented into Sport Tourers and Crossovers, the SUV segment continues to grow. Honda’s Pilot takes minivan space and functionality, adds all-wheel drive, and goes gunning for the middle of the market. The Volvo XC90 is the only other product that provides anything of interest in this segment.

Volvo XC 90
Volvo’s XC 90 has successfully translated its basic styling cues (raised hood section, beveled shoulder line) into an SUV without going over the top. The traditional chamfered front and rear corners are not only maintained but deepened to create a distinct shoulder line along the body side. This evokes a more muscular, refined feeling, but doesn’t stray too far from the look found on Volvo’s V70 and all-wheel drive V70 XC wagons. Structurally, Volvo places its safety stamp on the XC 90, by reinforcing the roof structure with Boron steel to reduce the chances of it crumpling in a rollover, and by adding a lower crossmember to the suspension subframe to enhance crash compatibility with lower-riding vehicles...like the S80 on which the XC 90 is based.

Honda Pilot
This is the first large SUV for the Honda division designed by Honda engineers, and the second SUV Honda has produced from the basic Odyssey minivan platform. Unlike the Acura MDX, the Pilot’s exterior is a study in unadorned utility. In front, the Pilot is much squarer than its counterpart, though Honda claims that it offers best-in-class aerodynamics, partly due to the use of underbody strakes. (The MDX has a Cd of 0.36, though Honda won’t say whether the Pilot’s coefficient of drag is better, or by how much.) Not surprisingly, Honda has produced an unobjectionable box designed to house a cavernous interior. Though official figures are unavailable, off the record Honda engineers say the Pilot is within two inches of the Ford Explorer in length, but at least two cubic feet larger inside. It has a carrying capacity of 3,500 lb., and can tow a total of 4,500 lb.

Sedans: Not dead yet Distinguishing Characteristics: Four doors, “three-box” shape, the cargo segregated from the passengers. On-road only. Lower ride and overall height. Natural Habitat: Cities and suburbs. Comments: Despite the overwhelming number of truck-like vehicles emerging, the sedan segment shows signs of life. At the top of the list are Lincoln’s modern interpretation of the 1961-1963 Continental, and Infiniti’s surprisingly technical G35.

Lincoln Continental
The suicide doors, which open to create an aperture nearly five feet wide, are the most noticeable feature of the Continental concept. A large central console combines with a “ring frame” to tie the sills, pillar posts and roof rails together, and return rigidity to what otherwise could be a very flexible structure. The doors attach to the structure by means of “bayonet” locks located at the top and bottom of the doors that attach to the sills, and chrome “push buttons” on the front doors that fit into receptacles on the rear doors. These electrical contacts ensure the doors are properly closed. In addition, the rear roof pillars are angled to grant rear seat passengers unobstructed vision, while still giving them privacy. Plus, the hydraulically powered decklid raises and retracts horizontally. This allows easy access to the three sliding storage drawers in the 20.5 ft3 trunk. Chrome fender caps accentuate the car’s length, and slim side marker lights fit in the body side “seam.” The latter makes for exacting assembly tolerances, and the choice of overly large taillights all the more perplexing.

Infiniti G35
Like most race cars these days, Infiniti’s G35 sedan (a coupe follows this fall) was developed in a moving ground plane wind tunnel. It has a Cd of 0.27, zero degrees of front lift, and produces slight downforce with the optional rear spoiler. The bumpers and headlights are shaped to direct flow toward the tops of the fenders, and draw air across the front brakes. This also helps scavenge hot air from under the aluminum hood. Combined, the raised rear trunk and rear glass angle improve airflow, improve trunk space, and keep water from collecting on the window. Dual front bulkheads reduce noise intrusion and increase body rigidity. High intensity discharge xenon headlamps are available as an option, while the rear LED tail lamps are standard equipment. Starting price for the 260-hp G35 is a surprising $27,100.

Minivans: Evolutionary perfection? Distinguishing Characteristics: Four doors (two hinged, two sliding), “one-box” shape, one-piece tailgate, prodigious people and cargo-hauling capabilities Natural Habitat: Found near home, supermarket and band practice, with semi-annual migrations during the summertime and holiday seasons. Comments: Minivan customers are the most resistant to change of any segment’s buyers because their purchase is based almost entirely on utility and reliability. That makes it more difficult for designers to break out of the box and pen something new. One to emerge is the Nissan Quest.

Nissan Quest Concept
The Quest’s beltline consists of two arcs: one begins at and includes the headlight and a second that rises dramatically and ends with the taillight. This character line is a wide, sharp-edged bevel that angles down and away from the vehicle and that will make the stampings for the doors and rear quarter panels more complex. Similarly, the shape of the front fenders require a die that will need to be more intricate than those of the Quest’s slab-sided counterparts. Higher up, the designers have chosen to completely de-emphasize the body’s pillars by hiding them behind a wraparound glass treatment. The Quest also incorporates what may be the best minivan innovation since the Honda Odyssey’s hideaway third seat–a bi-fold tailgate that folds in half to ease loading in tight spaces. It may well find its way onto the production version built at Nissan’s new plant in Canton, Mississippi.