Saab's 9000 has been around in various forms since 1986, and its replacement, the 9-5, is slated to arrive next year. That's a run of 11 years, which demonstrates remarkable staying power in a period of rapid change in the automobile business. This year is Saab's 50th anniversary, commemorating the public introduction of the Saab 92 in 1947. Powered by a two-stroke, two-cylinder engine, the teardrop-shaped 92 looked like the fuselage of a small airplane without wings, which is not surprising since Saab is an acronym for Svenska Aeroplan Aktiebolaget, a Swedish aircraft company. Today's 9000 is a far cry from that original car, but the philosophical underpinnings remain the same. Function takes precedence over fad, all controls and instruments are oriented to serve the driver and over-the-road performance is its strength. Although the 9000 was initially introduced as a five-door hatchback, it has evolved into a four-door notchback with a more traditional profile as well as a separate trunk. Luxury hatchbacks don't sell as well as sedans, thus the change. There are three versions (CS, CSE and Aero) with four engine choices, three of them turbocharged, 2.3-liter four-cylinders with output ranging from 170-horsepower to 225-horsepower. The fourth engine is a 3.0-liter V6 with 210 horsepower. Our test car the anniversary model CSE, which comes loaded with power sunroof, leather upholstery, Walnut-trimmed instrument panel, trip computer, heated seats, power windows and locks and an AM/FM stereo with CD player. Its 200-horsepower engine gave it energetic acceleration. With one person aboard, full-throttle acceleration caused the front wheels to twitch as they grabbed for traction. With four people inside it was slower on take off but still rolled strongly at freeway speeds. For those who want more scoot, the Aero model, starting at $41,495, is quicker still. Saab has long been a pioneer in turbocharging to extract power from a small engine. The turbocharger is a turbine driven by gases from the exhaust system. The harder you drive, the faster the turbine spins and the more air it blows into the engine. An advantage to a system like this is that the engine gets relatively good fuel economy when driven easily, yet has adequate power when you need it. Inside, the 9000 has the interior volume of a large car, even though its 105.2-inch wheelbase and 187.4-inch overall length is more like that of a mid-size. All gauges and instruments are grouped close to the driver to make them easy to reach, but some are not as ergonomically friendly as newer models. The stereo sounds good, but using it is confusing because it has too many tiny buttons and unclear markings. Versatility and utility are Saab trademarks, and even in the CSE they remain important. The emphasis, it would seem, has shifted more toward luxury, and that detracts from its flexibility. As an example, folding down the back seat is fairly compli cated, requiring removal of headrests and tilting the bottom seat cushion forward before the back can tumble forward. It is not as convenient as the original hatchback. Power window switches are mounted on the console, which is fairly common for European cars but less handy than being on the door panel. The two-tone upholstery of our test car was bright without being gaudy, although it may not suit everyone. The orthopedically designed front seats are quite comfortable. The 9000 has had a long and successful run, but it is time for a change. Next year's 9-5 will be interesting because it will reflect input from Saab's partner General Motors. Price The base price of our CSE test car was $38,995, and the only option was $180 for special paint. The sticker price was $39,700. Warranty The basic warranty is for four years or 50,000 miles. Vehicles for The Star's week-long test drives are supplied by the auto manufacturers. Poin Even though the basic 9000 design is more than 10 years old, it still offers strong performance and a spacious, versatile interior. Counterpoint: Folding down the back seat is not as easy as it should be, window switches are mounted on the console and the stereo's tiny buttons are too complex. SPECIFICATIONS: ENGINE: 2.3-liter, 4-cyl. TRANSMISSION: Five-speed WHEELBASE: 105.2 inches CURB WEIGHT: 3,250 lbs. BASE PRICE: $38,995 PRICE AS DRIVEN: $39,700 MPG RATING: 20 city, 29 hwy.