By Andrew Ganz
Wednesday, May 12th, 2010 @ 12:00 pm

For decades, BMW has tightly held onto the recipe for the quintessential small sports sedan by lightly improving its basic strategy with each redesign. We like to think that the BMW Way is locked up alongside the Coca-Cola formula at the SunTrust bank in downtown Atlanta.

But every time we ask BMW, we’re met with the same blank stares. Usually, the company’s German engineers reach for their Men In Black memory erasing pens, but the affable public relations types are good about stopping this behavior – although it’s worth noting that the Leftlane credit card shows some pricey bar tabs (if you can call those places bars) from the last time we hung out with Hans and Frans from BMW. But, uh, we don’t remember that night.

What we can remember is the last time we sampled a BMW 335i; we fell in love all over again with the sublimely smooth sports sedan that essentially defines the segment. With spring turning into summer soon, it seemed worth our time to check out the 335i Convertible.

What is it?
Now in its fourth generation, the 3-Series Convertible has become ubiquitous with well-heeled sun worshippers coast-to-coast and even in between. Realizing that not all of the sporty droptop’s buyers live in the sunbelt, BMW swapped out the insulated softop of the past three generations for a folding metal hardtop designed to bridge the gap between coupe and convertible.

Once a technical spectacle, folding metal roofs have become increasingly common; nowadays, it’s more unusual to find a droptop in this class that eschews the hardtop style for a “classic†ragtop.

Our 335i Convertible test car was loaded up with the optional navigation system, which meant that the infamous iDrive control knob sprouted from the center console just aft of the six-speed manual transmission lever.

Now about midway through its life cycle, the E90 3-Series platform has garnered critical acclaim from nearly every outlet – including Leftlane, as we discovered last year when we sampled a four-door 335i sedan.

We’re anxious to spend more time in the upcoming 2011 model, which swaps out the current twin-turbo 3.0-liter six-cylinder for a single twin-scroll turbocharged unit promising more responsive power and improved fuel economy. Stay tuned.

What’s it up against?
Potential hardtop convertible buyers should add Infiniti’s G37 and Lexus’ IS 350 C to their list, as well as the less powerful (but also cheaper) Volvo C70. If you can live without the hardtop, Audi and Saab offer ragtop variants of their A5 and 9-3, respectively.

Any breakthroughs?
Folding hardtops aren’t quite the conversation starter they once were, although you’ll still draw a crowd in even the most unlikely venues should you choose to raise or lower the “folding wonder,†as a bystander in a parking lot called our 335i’s roof after watching it through its motions. Ford first tried a folding metal roof back in the ’50s, but the design took a 40 year hiatus until the Mitsubishi 3000GT offered one up in the mid-’90s.

We didn’t want to dilute our admirer’s fascination, but we could have pointed out that even the Chrysler Sebring can be ordered with a retractable hardtop.

The wow factor has officially become the oh factor.

Otherwise, it’s mostly business as usual for the 3-Series. BMW has further tweaked its iDrive system to be easier to operate while on the go. The lineup received a few tweaks for 2009 and it receives a few more for 2011; a redesign is still a few years off for the convertible.

How does it look?
Top-up, the 335i Convertible is almost indistinguishable from its coupe brethren. It’s only until you push the dashboard mounted top button that things change while the top performs its trick and hides away under the long rear deck lid. For what it’s worth, the top requires no effort beyond pressing a button.

Crisp and typically Teutonic in its design, the 3-Series was spared most of controversial former BMW designer Chris Bangle’s flame surfacing. The 3 is BMW’s biggest global seller and thus exhibits more of an evolution-over-revolution design language.

Last year’s update brought with it revised front and rear fascias as well as new head and tail lamps, which subtly keep the design fresh.

The 335i is distinguished from its naturally-aspirated entry-level (in the U.S. market) 328i primarily by a pair of round chrome exhaust outlets poking out from the rear bumper and a unique set of wheels. Those twist-spoke 18-inchers are reminiscent of a number of recent BMW concept cars and they suit the 3-Series Convertible quite well.

And on the inside?
Settle into the driver’s sport seat – which features nifty power adjustable bolsters – and it’s an all-business affair, the same basic theme that has guided BMWs since the 3′s grandfathers pioneered the compact sports sedan more than 40 years ago.

Simple, round gauges are visible through a steering wheel that dreams are made of. We’d like to order this thick and grippy three-spoke wheel with minimal auxiliary controls for every vehicle we own – even our riding lawnmower would benefit from BMW’s sport wheel. It really is that good.

Typical BMW switchgear flows through the center stack, although the large, high resolution monitor at the top is reserved only for navigation and iDrive-equipped cars. We’re still not 100 percent sold on iDrive, but 2010′s system is leagues ahead of the first setup that debuted nearly a decade ago. The controls are generally logical and easy to use, but we still struggled to do simple things like change the radio station and store presets.

Our test car’s contrasting saddle brown over black carpet interior was refreshingly warm – a stark contrast to the often Teutonically cold interiors we’ve come to expect from, well, every BMW since that iconic 2002 and its siblings. That said, we weren’t blown away with the overly glossy wood trim that doesn’t really stand out from its black surroundings. At first glance, we didn’t even realize it was grained; a brighter or matte finish wood or aluminum would (wood?) work best.

There is plenty of room up front to get comfortable, even if we wish the front seats offered adjustable lumbar. The rear is really only suited to children, but at least the trunk is reasonably capacious for a convertible with a folding metal roof. It’s worth noting that the roof loses quite a bit of volume when the top is stowed – but that’s nothing unusual for the class.

But does it go?
We’re looking forward to spending more time in the new twin-scroll turbocharged 335i, but for now the 2010 continues to impress. Virtually no hint of lag is followed by the kind of strong and sonorous power that makes you giggle every time you play with the skinny pedal. Officially, the 335i is rated at 300 horsepower peaking at 5,800 rpm, but the big news is the 300 lb-ft. of torque on tap from as little as 1,400 rpm. That’s just above throttle tip-in and it endows this convertible with seemless grunt. Think of the gas pedal as an easy-to-modulate on-off switch and you’re getting close.

Paired to BMW’s oh-so-perfect six-speed manual transmission and we’re pretty much in automotive bliss. Quite simply, no automaker has ever been able to pair transmissions and powertrains as well as BMW – although the rivals are getting better every day. The row-it-yer-own-damn-self transmission might have fallen out of vogue with all but the most seasoned enthusiasts, but that doesn’t mean BMW has given up. It provides crisp and buttery smooth shifts with just enough pressure required for the clutch.

Chopping off the top inevitably means some loss of structural rigidity, although you wouldn’t know that with the top raised. The structure is bank vault stiff over even the worst pavement, which our test car’s Sport Package gladly soaked up despite riding on low profile run-flat performance tires wrapped around 18-inch alloy wheels.

Drop the top and you’ll notice ever the faintest scuttle shake primarily evidenced by a rearview mirror that doesn’t especially like to stay still. But relative to most droptops on the market, the 335i Convertible is among the best.

Like the 335i sedan we tested last year, the 335i Convertible was born to play when the going gets curvy despite its somewhat portly 4,001 lbs. curb weight. With minimal body lean and BMW’s typical highly communicative steering (our tester was not equipped with Active Steering), the 335i carved through our rural test route with aplomb, making every curve seem almost video game-like in its unrelenting precision. In fact, the 335i managed to best its sedan cousin by letting us hear more of the pleasantly raspy exhaust that was too muffled in the four door.

Put the top up, however, and road and wind noise go mostly unnoticed.

The 335i drinks premium fuel, but at least we were able to record more than 31 mpg on a highway jaunt and around 22 mpg in mixed driving. That’s a lot better than the EPA’s 17/26 estimates; even in hard driving, we never saw below 20 mpg.

Why you would buy it:
The 335i Convertible is everything we love about the 335i sedan – but in a package designed to appeal to sun worshippers.

Why you wouldn’t:
Cheap it ain’t.

Leftlane’s bottom line
Neither quite as attractive as the A5 nor as value-laden as the G37, the 335i Convertible is nonetheless an absolute delight to drive. That the package includes a folding metal hard top only adds to its desirability for drivers who live where the sun don’t always shine.

Offering as close to flawless a driving experience as you’ll find in this class, the 335i Convertible sets the dynamics and packaging benchmark yet again. We just can’t wait to spend a little time with the new six-cylinder.

2010 BMW 335i Convertible base price, $51,200. As tested, $59,525.
Metallic paint, $500; Premium Package, $1,650; Sport Package, $1,400; Cold Weather Package, $900; iPod adapter, $400; Comfort Access keyless system, $500; Navigation, $2,100; Destination, $875.

Words and photos by Andrew Ganz.