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Note: Since writing this review, we have tested several other Mercedes-Benz cars, none of which had the quality problems described here.

Here's a piece of trivia for you: Mercedes-Benz is the only automaker in the American market that has offered convertible vehicles without a break for the last half-a-century. Everyone else dropped their ragtops in the mid-1970s. It wasn't until the mid-1980s that convertibles began to make a comeback, but Mercedes hung in there.

Now Mercedes is introducing its latest generation CLK cabriolet. Based on the CLK coupe launched last year, the 2004 CLK cabriolet features a fully automatic soft top and sensor-controlled pop-up roll bars disguised as two rear head restraints. Not only is the convertible top fully automatic for the first time on the CLK, but it can now also be operated remotely with the key. While the CLK cabriolet can provide open-air driving pleasure at the touch of a button, its top is also designed to ensure year-round comfort and low interior noise.

As with the CLK coupe, Mercedes offers three cabriolet models in the U.S. market. The CLK320 -- the model we tested -- is powered by a 215-horsepower, 3.2-liter V6, while the new CLK500 uses a 302-hp, 5.0-liter V8 like the SL500 roadster and the larger CL500 coupe. In addition to the larger-displacement V8 engine, the CLK500 cabriolet is equipped exclusively with 17-inch AMG wheels and a body design package, plus larger brakes and additional detail differences from the CLK320.

The latest CLK line is identified by a new version of the traditional Mercedes coupe/roadster front-end design, placing the three-pointed star in the center of a low, wide grill that blends with the now-signature Mercedes-Benz face. What appear to be four lights are actually two ellipses that form a single unit on each side.

The original CLK cabriolet's ability to carry four people and their luggage helped the car succeed in a market segment that has since seen other luxury cabriolets disappear. The current CLK is even roomier and more practical than its predecessor, adding rear headroom, elbow / hip room and knee room.

The CLK line uses a strut front suspension with split lower links, and the rear suspension is a refined version of the patented multi-link design used on all Mercedes passenger cars. A new, lightweight rack-and-pinion steering system provides steering precision and a quick response. The CLK also features speed-sensitive parameter steering, which provides ample power-steering assist for easy parking and low-speed maneuvers, then reduces the boost at speed for optimal road feel.

All CLK models feature "staggered" wheels and tires (wider, lower-profile tires on the rear). The standard setup for the CLK320 includes seven-spoke 16 x 7.0-inch front wheels with 205/55 HR16 tires and 16 x 8.0-inch rear wheels with 225/50 HR16 tires. The CLK500 uses larger 17 x 7.5-inch front wheels with 225/45 ZR17 tires and 17 x 8.5-inch rear wheels with 245/40 ZR17 tires.

The CLK interior is stylishly sporty, rich and well-appointed. The instrument panel uses analog gauges -- just like God intended -- and vertical LCD bar graphs for the fuel gauge and the coolant temperature. Standard luxury features include dual-zone electronic climate control with a sun sensor to optimize air distribution and a separate blower for the rear seats to ensure optimal comfort for each passenger.

A Bose premium sound system uses eight strategically located speakers and digital processing to actively adjust system output to compensate for ambient noise. The 10-way adjustable power front seats are unique to the CLK line. When activated by the driver through the settings in the multi-functional display, the seat and/or steering column will automatically move to create more space for easier entry to or exit from the vehicle.

The CLK steering wheel comes from the SL coupe/roadster and is power-adjustable for tilt and reach. Rocker buttons on its spokes provide an easy and convenient way to control many of the car's systems. The display in the center of the speedometer is linked to illuminated buttons on the steering wheel, allowing the driver to view the selected radio station, a personal phone book or even navigation instructions when the optional COMAND system with GPS navigation is ordered.

Rain-sensing windshield wipers, entrance lights and auto-dimming mirrors are standard. The bi-level glove box accommodates the optional 6-disc CD changer, leaving a lower shelf for personal items. The center console houses an adjustable-height armrest that also doubles as a storage compartment.

The optional COMAND system integrates the display and controls for GPS satellite navigation, the premium audio system and the optional cellular telephone. An optional voice-operated system controls both the major telephone functions and the audio system. Other options, including Parktronic parking assist, ventilated seats, an electronic trunk closer and a wood/leather steering wheel, bring even more premium-level luxury to the new CLK.

The CLK line also features the latest Mercedes-Benz safety technology, including dual-stage front airbags, rear side airbags and – on cabriolet models – new head/thorax sidebags in the front. Impact severity is the primary factor in determining the deployment force of the front airbags. However, deployment of the front passenger seat airbag is further influenced by sensors in the seat cushion that can classify the occupant weight, or by the sensors in the BabySmart system that inhibit deployment when the BabySmart child seat is properly installed. A full array of Mercedes safety inventions are also present, including ABS anti-lock brakes, straight-line traction control, ESP stability control, and Brake Assist.

If any one of the CLK's airbags or seatbelt tensioners deploy, the standard Tele Aid system immediately generates a direct call to an emergency response center over a dedicated cellular line with redundant antennas. The vehicle's location is provided to the response specialist at the other end by GPS satellite transponders. If needed, emergency response can be summoned immediately, with exact vehicle location, plus full information on the car model and color for quick recognition by emergency services.

At least that's the way it's supposed to work. The sensors in our car wigged out on us and sent a FALSE signal that the airbags had deployed. This would have been a minor inconvenience -- trying to convince the disembodied voice coming through the radio speakers that there had been no accident, the airbags had NOT deployed and, no, Mr. Bonsall did NOT require medical assistance -- but it went much further than that. The electrical system in the car is designed to largely lock-up when the airbags deploy. So even though the airbags had not deployed, the system, thinking they had, extended the headrests (the sensor-controlled pop-up roll bars disguised as two rear head restraints), froze the convertible top in place, and displayed a permanent warning message on the instrument panel that overrode all other computerized message functions.

We have never had anything of the sort happen to a test vehicle from any manufacturer, and we've been doing reviews since 1982. Thinking it was just a matter of flipping a switch somewhere to recycle the system -- or something simple such as that -- we took the car to the nearest Mercedes dealer. The service technician we spoke with -- and who shall remain nameless because he probably needs his job -- showed no surprise at all at what had happened. He told us repeatedly that Mercedes is simply packing too much in the way of electronics into their cars these days and this sort of mess happens all the time.

How big a mess was it? Two or three computer modules needed to be replaced or elaborately reprogrammed, and doing so would involved ripping out much of the car's interior. Of course, it was all covered under warranty, but still…

While most buyers will shed their cars after two or three years, older examples of these models are likely to be extremely expensive to maintain. So if you do decide to go for a CLK and plan to keep it for a while, this is one instance where we would advise buying all the extra-cost supplemental warranty coverage you can get.

In sum, we liked the CLK320 for its handsome styling and good performance. We were, however, greatly disturbed by the electronic calamity we experienced. Furthermore, the next Mercedes test vehicle we got -- an S500 -- also experienced an electronic failure, although of a different nature. (See our S500 test for more.) At a sticker price of $53,000 or thereabouts, a buyer has a right to expect a car that works. Mercedes-Benz, a company long known for top-notch quality, needs to do some hard work -- and fast -- if it is going to maintain that reputation. R&D