Of course, BMW's breadwinner couldn'twear just any old tin-top. the company'sdesign ethic doesn't include the flyingwedges and chin-high beltlines that offerconvertible-top designers a convenientplace to pile the metal and glass out ofsight. no, for the Roundel regulars, the junkin-the-trunk look would never do, and theexisting three-piece-roof designs in use oncompetitors like the volvo c70 and vW eoswere all deemed too bulky. so the companyteamed with its german softtop collaboratoredscha Ag to design what it claims is theslimmest-stacking top in the business.

Indeed, the new top not only disappearsbelow a trunk that looks similar to the coupe's,it even preserves 7.4 of the 12.3 cubic feet oftrunk space available when the top's up. thatslimness exacts a slight aesthetic penalty,however. two of the rods that guide the frontsection back over the middle remain in viewwhen the top is closed. they're disguised asa couple of rubstrips running the length ofthe roof, but it's a less clean look than thecompetition offers.

The new top mechanism consumes verylittle rear-seat width, so shoulder and elbowroom increases by 3.2 and 4.8 inches, andthe side glass is 30 percent larger providingan airier view out. sparse legroom will elicitgrimaces from rear-seat riders over fivefoot-six, however, so vacationers will likelyuse the back seat for luggage. toward thatend, the rear seatback folds down to forma flat carpeted shelf and preserve the seatleather. BMW even offers a custom-fit bag tofill this space. there is a trunk pass-thru, butit's big enough only for golf clubs and skis,and it can be accessed with the seatbackup and the center armrest portion removed.Loading luggage in the trunk with the topdown is tricky. customers opting for the $500comfort Access (keyless starting) packagecan use the key fob to raise the folded topout of the way and load the trunk, but thedecklid pivots backward so the gear has togo in over the gunwales. It's far clumsier thanthe volvo/Mercedes approach of raising thetop stack with the trunk open normally.

Opening and closing the top takes justover 20 seconds and can be done fromoutside the car with the comfort Access keyfob. operating the top with the car in motionis verboten for legal reasons (pivoting thetrunklid back obscures the license plate).other convertible highlights include anaccessory windscreen that can be installedby one person from the driver's side of thecar and leather upholstery treated with aninfrared-reflective pigment that can lowerthe temperature of dark-colored seats by30 degrees or more. the climate-controlsystem also switches to a top-down modethat redistributes airflow and relies moreon the outside-temp and sun sensors thanthe interior temperature monitors. safetykit includes pop-up roll-bars and front-seatside airbags with head protection.

Despite the fact that the steel roof and itsmyriad motors and hydraulics weigh 308pounds, the finished vehicle weighs just 440pounds more than the coupe. credit goes toweight-savers like plastic front fenders andmore astute structural reinforcements usingvarying grades of steel. torsional rigidityis up 50 percent, and indeed a 335i sportmodel sampled on smooth Arizona bywaysfelt snare-drum tight, with no dashboardshakes and just an occasional high-frequencyvibration following a bump impact with the topup or down. using the wind blocker, heatedseats, and climate-control system, the 3 seriesconvertible delivers quiet, comfortable, topdownmotoring in sunny weather at tempsas low as 40 degrees.

Perhaps the best thing about the newconvertible is that it exacts no greaterpenalty on the driving experience thanthat of carrying two pals with you in thecoupe. the steering is every bit as directand telepathic, allowing an unfamiliardriver to acclimate right away and exploreintuitively the limits of its adhesion. the 335i's300-horse twin-turbo intercooled enginemay have had a bit of tuning since our firstencounter last september; we felt no traceof turbo lag, whine, or whistle this time out.that's largely because the blowers are smalland tucked away down low in the enginecompartment. they serve only to fill in thelower half of the torque curve, achievingtheir peak boost of about 12 psi almostinstantly, and blowing their bypass valvesby 3000 rpm. from there on, it behaves likea naturally aspirated 7000-rev engine with10.2:1 compression.

Finally, please don't revoke our enthusiastlicenses for saying so, but the new Zfsix-speed automatic might be almost asdesirable as the ever-splendid stick. It's vastlypreferable to the infuriating sMg box. thesecret is its ability to operate with the torqueconverter locked almost all the time. duringsporty driving, lockup occurs right afterlaunch, and shifts are executed with lightningspeed (100 milliseconds, or as quickly asthe best ferrari f1 shifts). they're just asfirm, too. order a downshift with the steeringwheelpaddles (standard on 335i, optionalon 328i) and the revs blip. Jam the throttledown, and the optimum gear is selectedimmediately, without engaging intermediategears. the converter occasionally unlockswith a noticeable jolt while rolling to a stop,and accelerating from low speeds, whereone expects a bit of rubber-banding fromthe converter, can instead yield a jerky start,but one would quickly get used to this.

Increased computing power, astutehydraulic circuitry, and a patented torsionalvibration damper allow steptronic to offer allthe performance and most of the efficiency ofsMg and similar automated manuals withoutthe low-speed maneuverability, clunky partthrottleshifts, and other drawbacks. there'sroom for improvement on the sport-modeautomatic-shifting logic, however, which trailsthe best AMg units in its ability to intuit theperfect gear for every occasion.

With so many great ingredients, this 3 seriescab should age well and be rememberedas one of the great vintages—even thoughit comes with a metal cap.