If the R’s exterior resembles an arrow, you might imagine the upscale interior functions as the bow. The upper dash creates an unbroken horizontal plain, with the vertical center stack starting low within its own casing. The clear line of separation between the upper dash panel and the center stack sets up a front-to-rear flow of flat-surfaced storage consoles and controls that creates distinct seating areas. Materials such as wood, leather, and aluminum provide tactile and visual pleasure, as does the meticulous attention to detail throughout the cabin. Niggling complaints include distracting reflections from the windshield vent panel, and the less-appealing plastic used in the overhead console.

The 2006 Mercedes-Benz R-Class’s interior is understated, but notably luxurious. The cabin is a versatile living room for six, with large side doors that have deep armrests. Great grab handles situated above all four entry locations assist in entry and exit, as well as separate door openers and large leather-covered door pulls. Forward visibility is excellent between the raked A-pillars and through the side windows, with large mirrors providing a good view to the sides and rear. Adding more light to the equation is a regular sunroof ($1,390) or an optional panoramic sunroof ($2,490 for 5.5 feet of glass and a 30-inch opening to let the sun shine in). Each seating position has its own cupholder, seat adjustments, armrests, air vents, lighting, and entertainment choices.

Stowage is ample with nets and nests, door pockets, and a huge two-tiered glove box with a six-disc CD changer (standard on the R500 and optional on the R350). The standard audio system comes with an AM/FM/weatherband radio and a single slot CD player, and optional satellite radio. An auxiliary port to plug MP3 devices into the car’s audio is standard, and there’s an optional kit to connect iPods. Of note is the attractive gauge cluster with beveled edges.

An inch longer than the company’s flagship S-Class sedan, the new Mercedes R trumps its immediate competitor by a far greater distance. Cadillac’s SRX stretches 195 inches, a full eight inches shorter than the R-Class. And, when the SRX houses its optional three rows of chairs, the cargo capacity measurement of 69.5 cubic feet is well below that of the R-Class’s 85 cubic feet.

First- and second-row legroom is better in the SRX, but the Caddy’s third-row legroom spec, at 24.2 inches, is much tighter than the 32.4 inches available in the rear of the Mercedes, which we found ample in terms of legroom but a tad short in head room for those over six feet in height.

In comparison to its stablemate, the Chrysler Pacifica sports tourer, Mercedes has sacrificed some first- and second-row legroom in the R-Class for an increase in third-row spaciousness. Another in-house competitor, the E-Class wagon, seats up to seven passengers, but only offers 68.9 cubic feet of cargo space.