Because each was equipped with the optional Sport Package, both of our test cars had "multi-contoured" power sport seats, which we found comfortable. An additional seat adjustment, which tilts the upper section of the backrest forward independently, is a cherished feature. Likewise for the power-extending bottom cushion, though the gap it forms collects enough crud to clog a Dustbuster. We were satisfied with the front seats' overall comfort and dimensions, but we wouldn't have minded a little more front-seat legroom.

Despite the larger exterior, the 5 Series' interior isn't notably roomier than before. Most seating dimensions increase or decrease by no more than a tenth of an inch or so, though front headroom is up 1.4 inches, and there's an inch more shoulder room up there. Shoulder room is an inch narrower in the backseat. While it's workable, the backseat isn't exceptionally roomy. By the numbers alone, nothing in this class has impressive rear legroom, though we found the Infiniti M sedan's backseat more accommodating. The midsize luxury sedan class is dominated by rear- and all-wheel-drive cars, which mean a large center floor hump. Call them five-seaters if you want, but those center seats are less usable than in other cars.

Characteristic of BMWs, the 5 Series' cabin is relatively simple and spare, mostly in a good way. The instruments, though, are too plain in a market segment full of glowing electroluminescent gauges, though you can opt for a head-up display that projects crucial info onto the windshield. The 5 Series' interior is otherwise a deft exercise in restraint. The materials are high-quality overall, with elements like standard genuine wood trim, or real aluminum available as a no-cost alternative. One big sticking point for me — which, again, is par for the course with BMWs — is the standard leatherette (that's fake leather) seats in the 528i and 535i. Real leather is optional on these and standard on the 550i.

Though BMW has high-quality vinyl, the lack of real leather at these prices is hard to swallow. Archrival Mercedes-Benz is guilty of the same, but comparable models from Audi, Infiniti, Jaguar and Volvo all have leather to start, and some of those are priced lower.

Frankly, this isn't a new phenomenon for BMW, or even for the luxury class, where you're more likely to pay for features that come standard in the most affordable of vehicles. For example, practically every new entry-level car comes standard with a folding backseat, and, increasingly, an iPod connector. In the 5 Series, they'll cost you $475 and $400, respectively.

One after another of our editors remarked about the shortage of features at our 535i's $58,275 as-tested price. It had no navigation, no heated or cooled seats, no backup camera. On the upside, though some of these items are included in packages, you can also get them a la carte, so you're not forced to pay extra for something you might not want.

The standard sedan has a 7-inch display and an abbreviated version of the iDrive control system, which employs a multifunction knob/joystick and a cluster of buttons on the center console. With the $1,900 navigation option, the screen increases to 10.2 inches and includes voice activation and traffic information. iDrive controls many audio system functions, the telephone, the BMW Assist telematics system and numerous vehicle settings.

BMW's iDrive has earned disdain over the years, but the current generation is actually pretty good. To my way of thinking, the issue has never been how hard it might be to learn but how simple it is to operate once you do learn it, and that's the aspect that has improved. Don't let iDrive's reputation distract you from the true ergonomic foibles on this and other BMWs: I speak of the electronic gear selector and turn-signal stalk, both of which immediately spring back to a center position after you move them rather than stay where you put them. With this design, you lose the ingrained and perfectly natural feedback of a turn signal that's still on and a transmission that's in the gear you want. As a result, you're always looking for displays just to make sure you don't, for example, roll the wrong way when you lift off the brake.

Are these controls bothersome enough to break the deal for a would-be buyer? You'd be surprised, but the BMW faithful have overlooked such things because of the vaunted BMW driving experience. So how's that going in 2011?