VERILY, it is easier for a camel to pass through the eye of a needle than for a chubby eighth-grader to wriggle into the back seat of most four-door, three-row crossovers. Here is the functional impasse of vehicles like the Mazda CX-9, Volvo XC90 and Acura MDX: The opening for the rear doors cannot be made large enough for passengers to readily ingress the third row. Widening the rear-door openings results in something like the Mercedes-Benz R-Class, whose huge rear doors spread to the wingspan of a U2 spy plane, or the ears of Alfred E. Neuman.

What buyers of these vehicles really want is a minivan, a seven-passenger vehicle with large and convenient sliding doors on the sides. Oh, but heaven forfend! If you drove a minivan people might think you’re a . . . you know . . . parent or something! It seems to me the whole crossover segment is driven by a single, neurotic imperative to deny family status. Trust me, people: If you’re driving a big honking crossover with child car seats in the back, you’re not fooling anyone. You are soooo married.

But I digress. The key to three-row crossovers is rear-seat access, and it’s here that I think the 2008 Buick Enclave steals a march on the competition. With a simple lift of a lever, the Enclave’s second-row captain’s chairs spring forward and jackknife so that the bottom cushion folds against the front seat back, creating a large gap that passengers can step through to get into the back. Easy.

Now, this might seem a small detail, but this mid-row seat operation lends logic to the whole vehicle. In a lot of three-row vehicles — BMW X5, Jeep Commander, are you listening? — the third-row seats are so inaccessible they might as well be in Pyongyang. Why haul around all that steel and glass if you can’t use them?

For model year 2008, Buick has given the boot to the lustily loathed Rendezvous crossover, Rainier SUV and Terraza minivan and supplanted them all with the Enclave, which underscores its all-things-to-all-people mission statement. The Enclave — a full-size luxury crossover, available in front- and all-wheel drive, with the most-basic models starting at $32,790 — also carries the freight of reviving Buick as a premium brand, on par with Lexus and Acura. To that end, the Enclave’s spacious interior gleams with upscale polish and sham-glam details, such as the Deco-style Lucite cover on the gearshift indicator; the brightwork bezels around gauges, switches and air vents; the miles of French stitching on the optional leather; and extravagant use of imitation wood — indeed, enough to start a respectable imitation campfire.

Much of this works — the ice-blue instrumentation lighting, for instance — and some of it doesn’t. The vinyl on the central console has the smudge of accountancy about it. Also, the integration of the GM-issue components such as the nav/audio head and climate controls is less than artful. That said, the Enclave interior reflects a major investment in materiality, and the result is the best Buick interior since the 1950s. (By the way, Buick marketers, it’s “ambience,” not “ambiance.”)

There will be a lot of hearty back-and-forth about whether the Enclave meets or beats the standard for mass-class luxury, the Lexus and Acura. Not quite. But the deficits are small and fixable. For instance, the gearshift interlock button prompts a clacking sound from behind the instrument panel; the door locks activate with a reverberant “thunk.” And it’s a measure of just how far Buick has come that these grace notes of refinement should be in play at all.

On the outside, the Enclave subscribes to the squirrel school of design, in that it’s fascinated with bright, shiny objects. The front corners of the car are chandeliered with large headlight assemblies, in which the projector beam lenses are surrounded by fetching, cobalt-blue rings. There’s the suggestion of traditional Buick portholes in the chromic detailing on the hood. And there’s the can’t-miss-it audacity of the waterfall grille, which may or may not remind you of a pool-skimmer, depending on your state of mind.

At 201.8 inches long and 72.2 inches high, the Enclave is a big vehicle, and it’s a credit to the designers that they have managed to prettify this glorified school bus as well as they have. They have roped the fenders in large, muscular swells and lowered the hood line to give the Enclave a forward-leaning energy. I would not call it beautiful, but I think it has enough reckless dynamism to be at least interesting. Ten years from now, we’ll look at the Enclave and wonder what they were smoking, but for now, fine.

Buick has been drumming the phrase QuietTuning into our collective heads for a few years now, and the Enclave makes it real. This is a surreally hushed cabin that manages to all but mute the idling of the 3.6-liter V6. At highway speeds, the Enclave sails along in a great galloping whisper with just the barest runnels of wind turbulence wrapping around the A-pillars. The body structure is stiff, quiet and well isolated from the road. You’d have to give the Enclave top marks for ride refinement.

The converse is that this is a fairly numb and uninteresting driver. The biggest problem is its mass: The front-wheel drive Enclave is 4,780 pounds (with all-wheel drive, a wheel-bending 4,985 pounds). The six-speed transmission’s economizing shift logic makes the Enclave a little reluctant at mid-throttle, refusing to kick down into a lower gear without a hard kick in the slats. This was a particular bother as I was driving up the hill to my house.

This raises an interesting point, viz. the resurgent GM. I’ve now driven two GM products that were exemplary in every way but weight (the new and otherwise excellent Saturn Vue is also quite the porker). I wonder whether there’s been a strategic decision at the product planning level to de-emphasize curb weight in the interests of soundness and content. The problem with that is fuel economy: The Enclave gets only tolerable economy of 16/24 mpg, city/highway.

On the other hand, this is the first crossover to successfully unriddle the problem of rear-cabin access, so in a way, it’s one-third more efficient than vehicles carting around faux-row seating.