The Good: This 2006 Mini Cooper S Convertible gets extra horsepower from a factory-installed kit. The powered convertible top comes down easily, making the car an open-top fun machine, while the Harman Kardon stereo delivers rich audio. The Bad: Most of the interesting cabin tech is available only as a dealer-installed option. The price on our test car got within sight of 40 grand, pretty high for a Mini. The Bottom Line: The extra push from the John Cooper Works kit doesn't seem enough to justify the premium it adds to the price of the 2006 Mini Cooper S Convertible. We would have been happy to shave the kit and some other options off and just enjoy driving with the convertible top down, which is already part of the base price. Mini drivers who want to go fast will appreciate the tuner package on the 2006 Mini Cooper S Convertible with the John Cooper Works Kit, but they will have to be really dedicated to stomach the price tag. Beyond some extra horses and torque, driving with the top down on this convertible Mini can make for a particularly exhilarating ride. Other than the engine kit and the powered convertible top, this car isn't much different from the 2006 Mini Cooper S we reviewed earlier this year. This one also has a premium Harman Kardon audio system, but it lacks navigation, which is available as an option. There is also a nice array of dealer-installed options available, which weren't on our test car, including an auxiliary audio jack, iPod integration, a six-CD changer, and Bluetooth cell phone integration. The retro look of the Mini has undeniable appeal, yet it also manages a sporty appearance with its squat stance and hood scoop. And although it's a coupe, the rear seats offer enough legroom to take adults on short trips. Because of the convertible top, Mini adds large roll bars to the rear seats, which has the unfortunate effect of compromising rear visibility, something we wouldn't expect from a small car. But the convertible top makes an already fun car even more so. Mini enhanced the retro styling by making the cloth top able to roll partway back, creating a sunroof for driver and passenger, somewhat like cloth-covered sunroofs on older cars. Putting the top all the way down, which happens with the push of a button, makes the Mini the perfect car for cruising along the beach or an amazingly exhilarating ride when plummeting down the freeway at 80mph. Rich sound from Harman Kardon Although the eight-speaker Harman Kardon audio system doesn't have a subwoofer, it puts out solid bass. And it has no problem being heard during the aforementioned open-top freeway driving. The small size of the Mini makes it easier for the audio system to fill the cabin, and we were impressed by the overall rich sound, from deep bass to clear highs, of which the audio system was capable. The stereo on the Mini doesn't look like much, but it puts out great sound.Although the stereo does play MP3 CDs, the interface is pretty basic, with a single CD slot, preset controls, and a monochrome orange display that doesn't show MP3 ID3-tag information. As we mentioned previously, a six-CD changer, an auxiliary input, and an iPod connection are all dealer options. Other cabin technology includes a full-featured trip computer, which displays average fuel economy, instant fuel economy, average speed, and current speed. Power windows, dynamic stability control, and fog lights are all controlled from a series of plastic toggle switches below the climate controls in the center stack. A button that lowers all the side windows, front and back, sits above the rearview mirror, near the button for the convertible top. Extra horses from John Cooper Works But the major feature of this Mini, what will set it apart from most other Minis on the road, is the John Cooper Works engine kit. John Cooper Garages is a legendary company that made its name by tuning Minis for greater performance. It continues its work with the new, revived Mini by making a factory-installed engine kit that gives the car 200 horsepower at 6,950rpm, a gain of 37 horsepower over the Mini Cooper S. Likewise, torque is increased to 177 pound-feet at 4,000rpm over the standard car's 155 pound-feet at the same rpms. John Cooper's supercharger spins faster than the standard Cooper S supercharger, adding horses and torque.The John Cooper Works makes this extra power by using a faster supercharger, a new engine head that allows better airflow, and an engine control chip programmed for greater performance. In practice, the Mini doesn't feel all that powerful at low-rpm starts, but running the tach up makes the car feel like a rocket. One of our reviewers commented that he needed to keep an extratight grip on the wheel during acceleration. The increased power and excellent handling of the Mini is a recipe for bad behavior. The John Cooper Works kit shaves 0.4 seconds off the car's 0-to-60mph time, which comes in at 6.5 seconds, and gives it a top speed of 140mph. The six-speed manual transmission gives the driver plenty of options for putting the right amount of power to the wheels. It shifts very easily, and finding gears is no problem. Second and third are well-suited for twisty roads, while fifth and sixth lend to more economical driving on the freeway. Steering is tight in the Mini, and the handling contributes a large part of this car's fun factor.The John Cooper Works kit also includes a limited-slip differential, normally a separate option on the Mini Cooper, and sports brakes. The brakes offered good stopping power without being grabby. The limited-slip differential is an extremely valuable option on any type of Mini, and we think it should be a standard feature. The EPA gives the John Cooper Works-equipped Mini a rating of 22mpg in the city and 30mpg on the highway. During our mixed city and freeway driving, we observed 23.9mpg, which was fairly impressive considering our penchant for fast starts in this car. Road-holding from Mini With the increased speed of this tuned-up Mini comes a greater need for safety gear. Along with traction control and electronic brake distribution, which sends braking force to the wheels that need it most, Mini also includes Cornering Brake Control, which pushes brake force to the outside wheels if the brakes are applied in a corner. And, a surprising inclusion on a small car, the rear bumper is fitted with sonar sensors for park-distance control. To make up for the small amount of space to include a spare tire, our Mini was also equipped with run-flat tires, along with a flat-tire monitor. Because this Mini is a convertible, it has big, chrome roll bars sticking out over the rear seats. The doors are fitted with side-impact beams, and the front seats have front and side airbags. The Mini is rated with four stars for front and side impacts, and for rollovers. The Mini warranty covers three years or 36,000 miles of full maintenance, four years or 50,000 miles limited coverage, and four years or 50,000 miles of roadside assistance. Our review car started out as a 2006 Mini Cooper S Convertible, with a base price of $25,400. For looks, it came with Hyper Blue Metallic paint ($450), leather interior ($1,300), body-color interior ($200), and exterior chrome elements ($250). It also had the Premium package ($1,400), the Sport package ($1,900), and the John Cooper Works kit, which cost a whopping $6,300. All of this, and the $550 destination charge brought the total up to $37,750. We had a lot of fun with this car, and we give it points for that. But cabin tech is pretty minimal. Much can be added from the dealer, but dealer-installed options are rarely as well integrated as factory options. However, not much compares with driving a convertible Mini around on a sunny day. The John Cooper Works kit adds a little power, but maybe too little for the $6,300 premium. Ultimately, we have a hard time with $37,750 for a Mini. For around the same amount of money, there's the 2006 Acura TL, the 2006 BMW 325xi Sports Wagon, and the 2006 Honda S2000.