Buick Park Avenue is large and luxurious. It offers a smooth, comfortable, quiet ride. Its engine and transmission are smooth and quiet. Its controls are familiar and easy to operate. Its interior is roomy and comfortable and its trunk is huge. Park Avenue Ultra, the top model, is fast, stable and satisfying to drive. Its supercharged V6 engine delivers quick acceleration performance. While still reading the sheet music written for a large, front-drive American sedan, Ultra is surprisingly agile and responsive. It's equipped with StabiliTrak, a superb active safety system that can detect the beginning of a skid and help keep the car on its intended course by pulsing individual brakes. The Park is dated, however. Its interior is old-fashioned, and there are a lot of other, newer products out there. The standard Park Avenue offers a good value among large sedans, but the Ultra faces competition in its price class. Buick is striving to address this for 2003 by freshening the styling, updating the interior, and adding some useful features. The most noticeable change for 2003 is a throwback to an era when Buicks were world-class cars: portholes. Portholes are a Buick trademark introduced in 1949. Back in the Fifties they were called VentiPorts. Discontinued in the Eighties, portholes are back and are found exclusively on the front fenders of the Park Avenue Ultra. New exterior features for the 2003 Ultra include a new grille, monochromatic Buick shields, 17-inch chrome-plated wheels, and dual chrome-plated exhaust tips. Ultra's outside mirrors are fitted with turn-signal indicators for 2003, helpful for signaling other drivers on crowded freeways. Inside, the 2003 Ultra gets new burled walnut woodgrain trim, embroidered logos on the seats, new gauge cluster graphics, and bright aluminum door sills. The Gran Touring suspension with rear stabilizer bar is now standard on the Ultra along with lower profile tires on larger wheels, which provide better handling and a sportier ride.