Sport coupes have been around a long time, but few have been as unconventional as the 2006 Mazda RX-8. This nimble-handling machine is not only the only new production car sold in the world to have a rotary engine, it's also the only sport coupe to have a set of rear-opening doors that allows access to a surprisingly roomy four-passenger cabin.

These days, the Wankel rotary engine is pretty much synonymous with Mazda. Its advantages over a traditional piston engine include a higher specific output for a given physical size, a lighter weight and fewer moving parts. Mazda's latest "Renesis" rotary design has also minimized most of the traditional drawbacks. In the RX-8, Mazda's engineers were able to utilize the rotary's weight and size advantages to optimize engine placement. The result is a 50/50 weight balance between each set of wheels, a low center of gravity and a low hood line that contributes to the car's sporty style and a slippery coefficient of drag. The RX-8's base curb weight is about 3,000 pounds, about 300-400 pounds less than its main competitors. In terms of handling, very few cars achieve a better balance between handling precision and ride quality than the Mazda.

Although the idea of a "2+2" sports car has been around for decades, the RX-8 takes it to the next level via the "free style" doors in back, which open opposite the fronts and make loading people and cargo much easier. Provided they are under 6 feet tall, those seated in the back will find supportive seating and ample room all around. Alternately, the rear-seat area is a great place to throw luggage or grocery bags, though a synergy between it and the rear cargo area can't be obtained as the rear seats don't fold forward.

There aren't a lot of cars in the under-$30,000 sports car segment. But of the few, Nissan's 350Z is the RX-8's most direct competitor, as it offers similar performance for a slightly higher price. With no backseat, the Z is more of a true sports car, but for those who need a little practicality and a more forgiving ride, the 2006 Mazda RX-8 is hard to beat.

The Mazda RX-8 comes as a four-seat hardtop with, essentially, four doors. The front doors are full-size, while two smaller rear doors ease access to the rear passenger compartment. The RX-8 line comprises an automatic-transmission model with a new six-speed gearbox, and a manual transmission version that also has six cogs. The automatic RX-8 comes standard with air conditioning, 16-inch wheels and power windows, locks and mirrors. The six-speed manual model adds a limited-slip differential, a sport-tuned suspension and 18-inch wheels and tires. There are four option packages available. On six-speed models, the Sport package adds xenon headlights, stability and traction control and foglights, while automatic-equipped versions also get a limited-slip differential, larger brakes, a retuned suspension and 18-inch wheels. The Touring package provides a sunroof, Bose audio system, Homelink and auto-dimming mirrors. The Grand Touring package adds all of the above equipment, along with a six-way power-adjustable driver seat, heated seats, leather upholstery and heated side mirrors. The Shinka (Japanese for "Evolution") package adds both sporty and luxury features via a more aggressively tuned suspension, leather/Alcantara seating, Sirius satellite radio, upgraded interior trim and unique 18-inch alloys. Stand-alone options include a navigation system and an in-dash six-disc CD changer.

Both versions of the Mazda RX-8 are motivated by a 1.3-liter rotary engine that sends power to the rear wheels. When connected to the six-speed, paddle-shift automatic transmission, the engine is tuned to produce 212 horsepower. Manual-transmission versions get a 232-hp version of this power plant. Coupled with the vehicle's light weight, the RX-8 delivers exhilarating performance along with ultra-smooth power delivery. We've recorded zero to 60 mph in 7.0 seconds and a quarter-mile performance of 15.4 seconds with the six-speed manual.

Side airbags and side curtain airbags for the driver and front passenger come standard, as do four-wheel antilock disc brakes. Stability control is optional. In NHTSA crash testing, the Mazda RX-8 earned a four-star rating (out of a possible five) for driver protection in frontal impacts and five stars for the front passenger. The Mazda received four stars across the board for side-impact protection. Additionally, the RX-8 is the only passenger car currently sold in the U.S. to earn a perfect five-star rollover rating from the NHTSA.

Although the 2006 Mazda RX-8 has the look of a race-tuned sports car, its demeanor on the road is considerably more docile. There's plenty of grip in the corners and solid feedback through the steering wheel, but it won't beat you up on the daily commute. The rotary engine requires high engine speeds to make its peak power, but the delivery is virtually vibration-free and noise levels are subdued. Overall, the RX-8 is one of the best examples of a car that's fun to drive while still remaining livable on a day-to-day basis.

The RX-8's rear-hinged rear doors allow unobstructed access to the rear seats, giving this sports car the ability to comfortably carry four adults thanks to well-shaped seats and a roofline that allows ample headroom in back. The interior design carries a circular theme, with three round gauges and a circular central dash pod that houses the stereo and climate control functions, while "piano black" accents lend a touch of class to the cockpit. Unfortunately, an overly busy display for the audio system and climate control makes "at a glance" reading a challenge.