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.

Buick Park Avenue still looks graceful and quietly elegant. Its classic Coke-bottle shape projects a muscular grace, like a crouching cat. Buick's heritage is evident in the high, curved hip line, oval-shaped, vertically textured, forward-thrusting grille, bold horizontal taillights and slim, wraparound headlights.

Ultra sports a new vertical-bar grille, redolent of Buicks of yore and adding more masculine panache to the front end. Ultra's grille also carries a new translation of Buick's traditional tri-shield badge, now chrome colored and sharing the grille's more massive contours.

The portholes, set near the upper edge of the Ultra's front fenders, are functional. Buick says they allow airflow through their mesh inserts, which reduces underhood temperatures.

Also new for the Ultra are 17-inch chrome-plated alloy wheels, replacing last year's 16-inchers. The chrome looks a little bright to our eyes. We think a dull-coated finish would be more understated and more attractive. Out back, dual exhaust with chrome-plated tips are exclusive to the Ultra. The combination is sufficiently striking that it turned the heads of teenage boys who normally wouldn't even see a Park Avenue. The dual exhaust signals car enthusiasts of the Ultra's supercharged engine.

Park Avenue boasts is one of the roomiest cars available. It offer more interior room in both the front and rear seats than the Chrysler Concorde Limited and tops some interior measurements of the larger Mercury Grand Marquis. Big doors make getting in and out easy. Slipping into the seats is easy, and free of the simultaneous duck-and-bend maneuver required by swoopier designs. The roomy seats offer real move-around comfort, making the going positively serene, particularly during freeway cruising.

The interior is clean and tasteful. For 2003, Burled Walnut woodgrain (plastic, but it's nice) trim accents the dash and door panels. We question the need for the Buick Park Avenue logo on the passenger-side of the dash, however. Dual sun visors with extensions shield glare from almost every angle. The main instruments are covered by a gently arching nacelle that sweeps across the dash. Besides its contemporary appearance, this design allows room for a big speedometer and tachometer that are easy to scan.

Audio and climate controls use big buttons that are easy to find and operate when the car is in motion, and are visually set off from the rest of the interior by contrasting colors. The passenger temperature control for the dual-zone HVAC is located at the extreme right side of the dash, good for the passenger, impossible to reach from the driver's seat.

A trip computer allows the driver to calculate fuel economy and miles-to-empty. It also provides tire pressure, oil level and coolant level information. The Park Avenue's information system is controlled by a stack of clearly-marked buttons to the left of the gauges, and are easy to understand and operate. The trip odometer can track two trips, which can be useful on long journeys.

The Ultra adds premium CD sound, leather and power everything, which make the going more pleasant. The Concert Sound III stereo system, standard on Ultra and available on Park Avenue, comes with nine speakers, an amplifier, an integrated antenna system, and steering-wheel controls. A trunk-mounted CD-changer, part of the Ultra Luxury Package ($1,875), holds 12 CDs, enough for a drive from New York to Chicago.

Seating for six is standard, although the front-middle passenger may find the accommodations a little tight. We prefer the individual front seats ($185), which come with a new center console. (Our Ultra had the 5-passenger configuration included as part of the Ultra Luxury Package.) The console also includes two auxiliary 12v outlets and a rear seat heater/air conditioner vent. We found the lids on the center console awkward, but it provides a large amount of storage capacity because the shifter is up on the column. An overhead console is also part of the package, including reading lights and a universal transmitter for garage door openers or similar devices.

The optional head up display ($300) projects images that seem to float out the front edge of the hood. The display includes vehicle speed, turn signals and such. Some find it helpful, others annoying. Try it before you buy it.

Next Generation (reduced force) dual front airbags and side-impact airbags come standard. Park Avenue offers strong safety cage construction, and its doors are designed to automatically unlock within 15 seconds of an airbag deployment. Not surprisingly, insurance costs are low compared with other cars.

OnStar, GM's 24-hour on-demand driver assistance and navigation system, is standard on Ultra and optional on the base Park Avenue. Individually programmable Personal Choice key fobs control perimeter lighting, delayed locking, and memory settings for door locks, climate control, radio presets, seat adjustments, and inside and outside mirrors.

Park Avenue's trunk is almost large enough for an echo. It's slightly larger than that of the Chrysler Concorde, slightly smaller than the Lincoln Continental's. Gooseneck trunk lid support arms intrude on trunk space a bit, but offer the advantage of popping the trunk lid open when the button on the key fob is pressed, great when you have an armload of stuff.

Buick Park Avenue is powered by GM's proven 3800 Series II V6. This 3.8-liter engine delivers smooth, quiet power and brisk acceleration. The 3800 provides low-rpm getaway power, instant throttle response, and plenty of punch for passing. It's rated at 205 horsepower in the Park Avenue.

Ultra gets a supercharged version of this engine that produces 240 horsepower. This yields eye-opening acceleration when the pedal on the right is push all the way down. Do so only if you mean it, and be aware that acceleration from low speeds will tax the traction capability of the front tires. Make sure they're pointed where you want to go. The Ultra's supercharged engine is audible at full throttle, but we think it's worth a little extra noise to enjoy its superior thrust. This Buick can humble those pesky buzzing subcompacts driven by today's kids.

This is a front-wheel-drive car. Power is transferred to the front wheels through GM's butter-smooth electronically controlled four-speed automatic transmission. GM builds some of the best automatics in the business.

Park Avenue offers surprisingly good fuel efficiency, with an EPA-estimated 19 miles per gallon city, 30 mpg highway for Park Avenue and 18/28 mpg for the supercharged Ultra. We saw 24 mpg on mixed driving with the Ultra and more than 30 mpg for steady cruising.

Wind noise is a mere whisper. Only a slight ruffle of air could be heard around the A-pillars at higher speeds. Road noise is minimized by the stiff unit-body chassis, though some pavements yielded a whine from the low-profile 17-inch tires on our Ultra. The Park Avenue isn't quite as quiet as a $54,000 Lexus LS 430, but the distinctions are academic in most operating situations. The distinction in price is not academic in any situation.

There is a discernible difference in handling between the basic Park Avenue and the flagship Ultra. The base model behaves very much according to stodgy Buick tradition, floating atop its wheels, with pronounced body roll and vague power steering. If the Ultra's crisp handling and enhanced performance aren't important to you, then the standard Park Avenue may be the way to go. Standard with 225/60R16 tires, the Park Avenue comes well equipped and stacks up as a good buy among large cars.

Ultra offers tighter handling. With its supercharged engine and standard Gran Touring suspension, it can easily take on the best Lincoln and Chrysler have to offer. The Ultra's more positive control and firmer ride lend a contemporary feel that's a pleasant step forward for Buick. Don't expect BMW-like handling, however. The Ultra is tuned to American large-car sensibilities. The Gran Touring suspension includes wider wheels and low-profile Goodyear Eagle LS Touring tires (235/55R17). The stiffer suspension reduces the ride height slightly and yields much sharper responses in quick maneuvers. The tradeoff in ride quality is insignificant.

The Gran Touring package is available as an option for the standard Park Avenue ($285) and it's a good buy. It includes not only the upgraded suspension, wheels, and tires but also the leather-wrapped steering wheel and Magnasteer variable-effort steering that come standard on all Ultras. Magnasteer adjusts steering effort and ratio according to vehicle speed and steering angle, keeping effort low while still providing a significantly better sense of where the front wheels are pointed. The system is even dealer-programmable for effort and feedback should you want to tune your steering.

StabiliTrak monitors yaw rate (how fast the vehicle is turning) compared to steering-wheel angle (how fast the driver wants the vehicle to turn) and selectively applies the brakes to one or more wheels to help maintain control when there is danger of sliding or skidding.

Ultrasonic Rear Parking Assist ($295) can detect objects that are close behind the car but below trunk-lid level, out of the driver's normal field of vision. Shift into reverse, and the system transmits ultrasonic beams. Four sensors in the rear bumper detect echoes, and alert the driver with a chime. The system also activates three light-emitting diodes (LEDs) set in the rear headliner, where they are visible in the rear-view mirror. Ultrasonic Rear Parking Assist works at speeds up to 3 mph; at higher speeds a flashing LED warns drivers that they're on their own. It's real handy for parallel parking as it beeps faster and faster as the rear bumper approaches the other car, allowing the driver to back the car up very close to the other vehicle without touching it. We recommend it.

Buick offers two models: Park Avenue and Park Avenue Ultra.

Park Avenue ($34,075) comes with a 205-horsepower 3.8-liter V6 engine. Standard features include a cloth-trimmed interior, power windows, power mirrors, automatic climate control, cruise control, automatic headlights and other conveniences. OnStar, anti-lock brakes (ABS) and side-impact air bags are standard.

Park Avenue Ultra ($39,225) romps with the gusto of a 240-horsepower supercharged edition of the 3.8-liter V6. Trimmed in leather and wood, the Ultra adds heated 10-way power front seats, mirrors that automatically tip downward for parallel parking, a compass, moisture-sensing windshield wipers, GM's OnStar communications system, a premium stereo, and other luxuries. To complement its more powerful engine, the Ultra comes with traction control, StabiliTrak stability control, a heavy-duty transmission and Magnasteer speed-sensitive power steering.

Ultrasonic Rear Park Assist ($295) is a useful option that aids parking and enhances safety by sounding a tone and illuminating an indicator as the rear bumper approaches objects. Also available is a Head-Up Display ($300) that projects vehicle speed onto the windshield.

A Prestige Package ($2240) adds many Ultra luxuries (but not the supercharger) to the base Park Avenue. StabiliTrak ($495), the Gran Touring suspension ($285), and a sunroof ($1,095) are optional for the Park Avenue.

Buick Park Avenue is a comfortable sedan on rough city streets and for long highway jaunts. It offers traditional good looks, class-leading roominess, and many luxury features.

Park Avenue Ultra is the best of the line with its supercharged engine and touring suspension. Portholes now signal you've chosen the fast version of the Park.