The CLK is available as a coupe or convertible, with a V6 or V8 engine.Those who prefer understated, buttoned-down elegance will like the CLK Coupe.Extroverts and sun worshippers can choose the one-button convertible top on the CLK Cabriolet.

The CLK is one of the sportiest cars in the Mercedes lineup.It has rear-wheel drive in a class increasingly populated by front-wheel-drive and all-wheel-drive cars, and it has a sporting flair many mid-size luxury cars lack.

We think most drivers will be quite happy with the CLK350 and its 268-horsepower V6.With its seven-speed automatic, the CLK350 delivers a fine balance of spirited acceleration, quiet cruising and decent fuel mileage.The CLK350 gets an EPA-rated 17/25 mpg City/Highway.

Drivers who demand more performance can choose the CLK550.Its V8 generates 382 hp and an even more impressive 391 pound-feet of torque.(Torque is that force that launches the car from intersections and propels it up hills.) Measured by acceleration and engine response, the CLK550 meets just about any standard of high performance.The CLK550 transmits a feeling of being more stuck to the road than the CLK350 does, with sharper handling and better high-speed stability.

On the open road, the CLK, no matter the model, is satisfying, responsive and exceptionally stable at high speeds.It inspires confidence on twisty roads and bears up well in a spirited drive.It's also easy to live with.Its ride is firm, but not intrusive.Its relatively small size makes it easy to park and maneuver in crowded city centers, but its back seat is roomy enough for two adults.

In a word, the CLK is balanced.Its stylish design and elegant interior make it a pleasant place to spend time, and it delivers Mercedes cachet that works in almost any circumstance.

For 2009, two new Grand Edition models have been introduced.The Grand Edition CLK350 coupe will be in Palladium Silver paint with a Tobacco Brown leather interior with beige stitching and aluminum trim.The Grand Edition CLK350 Cabriolet will be in Diamond White with the Tobacco Brown leather trim and beige stitching and dark ash wood trim.Both versions will have Sport body styling and 18-inch alloy wheels, and there will be only 1,000 copies of the limited-edition models produced.

The CLK350 Coupe ($44,100) and Cabriolet ($56,100) are powered by a 3.5-liter V6, which develops 268 horsepower and 258 pound-feet of torque.

Standard features include leather upholstery, dual-zone climate control with pollen and dust filter, 10-way adjustable power seats with three memory settings, rain-sensing windshield wipers, and Sirius satellite radio.Black-stained ash wood trim is standard, and more traditional burl walnut is available as a no-charge option.The Cabriolet features a fully automatic, heavily insulated convertible top.

The CLK550 Coupe ($56,800) and Cabriolet ($64,800) get the 5.5-liter engine that generates 382 horsepower and 391 pound-feet of torque.

Options are grouped in packages: Premium 1 and 2.Exact content and price vary with the model.On the CLK350 Coupe, Premium 1 ($3,100) includes auto-dimming mirrors, a programmable built-in garage door opener, a premium harman/kardon stereo with six-CD changer and a glass sunroof.Premium 2 ($4,140) adds turning bi-xenon headlights with washers and a heated windshield washer system.

Stand-alone options include a navigation system combined with on-screen control for the stereo and air conditioning ($2,320), wood and leather steering wheel ($560), active ventilated front seats ($730), electronic trunk closer ($540), and Keyless Go push-button starting ($1,130).

Safety features that come on all CLKs include multi-stage front-impact airbags.Coupes get front passenger side-impact airbags that protect the torso, and curtain-style head protection airbags for both front and rear passengers.The convertibles combine both torso and head protection in the same side-impact airbags.The also feature pop-up rollbars that automatically deploy if the electronics sense a pending rollover.TeleAid accident notification is standard.Side-impact airbags for the rear passengers are optional ($400).Anti-lock brakes (ABS) with emergency Brake Assist and Electronic Stability Control are standard.

The CLK is a fairly compact car, based on a lengthened version of the same chassis used for the small Mercedes C-Class sedans.Yet the designers have successfully infused it with the presence and bearing of a much larger coupe like the big Mercedes CL.

The coupe aesthetic starts with the profile.The CLK dispenses with a center roof pillar, so the roof sweeps uninterrupted from the base of the windshield to the trunk lid.The rear windows lower completely below the sill, emphasizing the smooth, open flow, and the effect is enhanced by the absence of any visible antenna for the radio, telephone or navigation system.The CLK replaces a conventional steel trunk lid with a composite panel that allows the antennas to be imbedded into the lid's structure.

The second, unmistakable coupe element is the CLK's front end.This Mercedes forgoes the traditional hood ornament in favor of a lower, much larger three-pointed star set into the wide, three-slat grille, which greets the world with just a hint of a sneer.On first impression, it seems the CLK has four headlights, but a closer look confirms a single ellipse-shaped cluster on each side.And there's more to the headlights than slick design.The optional bi-xenon lights swivel to point into curves and are equipped with high-pressure washing jets; they also change beam angle as the CLK moves up and down with road imperfections, keeping the high-intensity light below the sight line of the drivers in oncoming cars.

When its fabric top is closed, the CLK Cabriolet is nearly identical in silhouette to the coupe, with only a hint of a break in the roofline where it meets the trunk lid.The fabric top is fully lined and insulated, and opening or closing it is a one-button operation.Roughly 30 seconds after the driver hits the button, the top tucks neatly under a hard cover behind the rear seats.Rollover protection hoops are integrated into the rear-seat headrests, allowing the same clean look when the top is down.In the event of an imminent collision or rollover in the cabriolet, two roll bars deploy and lock in place within 0.3 seconds.

Details distinguish the CLK models.The CLK350 has neutral-tinted glass and gray vanes in its grille, while the CLK550 has blue-tinted glass, high-gloss black vanes with chrome trim on the grille, and a short rear spoiler.

The CLK350 and CLK550 come with 17-inch wheels, slightly wider with fatter tires in back, to create the staggered-wheel look of a race car.The wheels on the CLK350 are a light-alloy five-spoke design.Those on the CLK550 feature an AMG-styled monoblock design.

The optional Sport Appearance Package for the CLK350 includes special six-twin-spoke aluminum wheels, a sports suspension that lowers the CLK slightly, and cross-drilled brake rotors that are visible through the wheels.

Materials are very good throughout.Soft polyurethane sprayed onto the dashboard provides an attractive appearance and a luxurious feel.Black-stained ash wood trim and black carpet is standard, though traditional burl walnut is available at no charge.Nice touches of wood and gathered leather on the door panels make for a very attractive cabin.

When front passengers close the doors, an electric arm on each side of the CLK extends to present the seatbelts, making it easier to reach the belts.The belt presenters retract once the belts are buckled.It works well, though we've seen passengers startled by them, fearing the return of the motorized mouse.

Most controls and switches, including climate adjustments and audio, are stacked in the center of the dash above the console.They're easy to locate and big enough to adjust without a lot of concentration.Standard features include digital dual-zone temperature control with a sun sensor to optimize air distribution.The rain-sensing wipers are operated with a stalk on the right side of the steering column.

Storage options have improved by Mercedes standards, but come up short when compared with other cars.The two-tiered glove box is large, but the optional CD changer will take up one of the shelves.The center console has two cup holders and a storage bin.

The gauge cluster is a mix of traditional analog gauges and LED graphics.A large round speedometer and tachometer dominate the center, flanked by two smaller, thermometer-like gauges for the fuel level and coolant temperature.It's both attractive and effective, with crisp illuminated script that's easy to read at a glance, though at first you may confuse full and empty on the gas gauge.

The CLK steering wheel is one of our favorites: Just the right size, thickness and firmness for this car, and power-adjustable for tilt and reach.Rocker buttons on its spokes allow operation of several systems, including stereo, climate and telephone.

These buttons also manage an LED information display in the center of the gauges.There's a wealth of information available, including trip functions such as average speed and distance to empty, but it takes a bit of concentration to scroll through and find what you're looking for.

Access to the rear seats is easier than it is in many coupes, but that's mostly because there is more room than in many coupes.The front seats help by tipping and sliding forward with a quick-release lever.If the front passengers don't have their seats moved too far rearward, there's enough room for two adults in back -- at least for traveling to dinner and a show, if not a cross country trek.

The rear seat folds down with a 60/40 split, and that's good.With 10.4 cubic feet of space in the trunk, the CLK will hold a load of luggage for two, but its trunk is smaller than typical in a sedan of its size.The fold-flat rear seat helps a bit with oversized items.

You won't lose much rear seat space with the CLK Cabriolet, but you will lose a lot of storage in the trunk, even when the convertible top is up.With the top up, there's enough space for four to six bags of groceries.When the top is down, it cuts the trunk space almost in half.Nonetheless, the top is thickly insulated and beautifully lined, and it's almost as pristinely quiet in the CLK Cabriolet as it is in the coupe, when the top is up.

The CLK suspension absorbs bumps without fanfare.The only disturbances might come from the tires going over potholes, and it's heard more than felt.The CLK is comfortable, but not numbing, so the steering feeds good information back to the driver about how well the front tires are gripping.

This balance of smoothness and road feel means you might be driving the CLK harder than you realize in fairly short order.When the straight, flat roads of the city give way to twisty two-lanes in the hills and countryside, the coupe handles curves with the grace of a thoroughbred.It maintains a nice, flat attitude through sweeping bends and won't bob or weave with frequent applications of the brakes.

We like the way Mercedes has refined its electronic stability program, which can help the driver maintain control by reducing skidding.In the CLK, the system is virtually transparent, intervening unobtrusively to prevent wheel spin, but without the heavy-handed reduction in power that marred some of its early applications.

Engine performance is satisfying in all models.The 268-hp V6 in the CLK350 has all the power most drivers need, accelerating with authority from a stoplight and moving the car smoothly through the gears.Acceleration times for the V6 match those for the typical V8-powered luxury car of the late 1990s, and there's a reserve of power that makes passing on two-lane roads a stress-free process.

Nonetheless, the 5.5-liter V8 in the CLK550 is a significant, noticeable step up, from both the CLK350 and the previous CLK500 models.With 382 horsepower and 391 pound-feet of torque, acceleration is thrilling.Capable of accelerating from zero to 60 mph in just 5.1 seconds, the CLK550 is high performance by nearly any definition.Slam the accelerator at any speed and what follows, almost instantaneously, is a satisfying, muted growl from the exhaust and a whoosh of speed.

Both the CLK350 and CLK550 are equipped with the seven-speed automatic, and we like this transmission.Beyond the extra gears, its control program works better than that on the Mercedes automatics of previous years.This one doesn't slack off when you need it most, quickly kicking down to a lower gear, and sometimes shifting down three gears at once if you slam the accelerator hard.Alternate shift buttons, which allow selection of a specific gear, are located on the back of the steering wheel hub, right where fingers wrap around the spokes.The touch-shift manual mode works nicely.

The brakes on the CLKs stop the car with authority, and deliver a nice, easy-to-modulate pedal feel that's distinctly lacking on some Mercedes models.

With its smooth aerodynamics, generally quiet manners and excellent anti-skid electronics, the rear-drive CLK Coupe is suitable for all-season use, in our view.Snow tires would remove any reservation, even in regions with lots of snow.

If you love top-down motoring, there's no real reason to pass on the CLK Cabriolet.With the top up it's almost as snug and quiet as the coupe.With the side windows up and fold-up windblocker in place, you could motor top-down on sunny days when the temperature is in the 40s.Best of all, there is no serious degradation in that tight, solid feeling that characterizes the CLK Coupe.Extensive use of high-strength steel alloys and liberal structural re-enforcements maintain the torsional stiffness and help minimize vibration.Mercedes claims the stiffness of the cabriolet's body is equal to that of the coupe, and we find no reason to challenge that assertion.Of course, those structural re-enforcements add weight to the Cabriolet, so owners are likely to see a slight reduction in fuel economy compared to the coupe.

NewCarTestDrive.com correspondent Tom Lankard reported from Santa Barbara, California; with Mitch McCullough reporting from Los Angeles, and J.P.Vettraino in Detroit.