"The relentless pursuit of perfection." Lexus adopted that slogan years ago and today no one is laughing. For the past decade, the Lexus brand has stood atop every meaningful measure of automotive excellence, dominating the annual J.D. Power lists for reliability, dependability and initial appeal.

And how has it been rewarded for its excellence? The LS430, subject of this test, is the best-selling premium luxury car in America. It defines automotive excellence for others. The "L" in Lexus now stands for leadership.

How could anyone have known in 1989 that this luxury car division of Toyota would rise so rapidly? The brand was new then. It was said then that Lexus used Mercedes-Benz as its target; rival Nissan used BMW as its target for the Infiniti luxury line.

Imitators, we thought. During the Lexus introduction at a 1989 auto show, a Cadillac executive laughed to the press about the idea of Toyota-maker of fine little economy cars, wink, wink-competing for buyers of Cadillacs, Lincolns and Mercedes-Benz's. Little did he know what lay ahead. Today, Lexus outsells them all.

Let me tell you a few reasons, besides reliability, that you'll love the Lexus LS430. It has:

o Adaptive cruise control with accident-avoidance capabilities.

The best navigation system I've yet tested. All of the U.S. and parts of Canada are on one DVD.

The best sound system, designed by Mark Levinson, available in any vehicle.

Air-conditioned seats!

Auto-dimming mirrors inside and out.

Both a rear-view camera that displays images on the navigation screen when the car is in reverse and ultrasonic parking aids front and rear.

Every safety feature known to man, including knee air bags for both driver and front-seat passenger.

Auto-on headlights and rain-sensing windshield wipers, and the headlights turn left or right 15 degrees to illuminate curves.

A driver's seat that adjusts 14 ways, with two lumbar supports, and never creates a backache after long drives.

Such good rear seats that the car could easily be chauffeur-driven. They recline like your easy chair and massage on command.

Quality construction that sets new standards for everyone else.

The Lexus LS430 accelerates from 0 to 60 in under six seconds, stops quicker than almost anything on the road, corners with sports cars, delivers 25 miles per gallon on the highway from a V8 engine, carries five comfortably, and has a coefficient of drag of 0.25, better than a Corvette, Audi TT and most any other car you think is sleek.

Lexus focuses safety concerns on avoiding an accident and minimizing injuries to those inside should an accident occur. To avoid an accident, the LS430 has a highly sophisticated computer control system that maximizes traction during acceleration and turning. Should the car go into a sideways skid, for instance, the Vehicle Skid Control system will back off the throttle and apply braking to wheels that will help correct the skid.

If it believes an emergency stop is needed, it will maximize the anti-lock brakes even if pedal pressure is less than full. If it senses an accident is imminent, it cinches the seat belts and locks down its occupants. If the accident occurs, an onboard computer determines the severity and deploys the appropriate air bags as explosively as needed (air bag injuries often occur at low speeds where much less explosive force would have sufficed).

Should the LS430 be in a serious accident, the onboard computer, coupled with the navigation system and wireless telephone service that uses Bluetooth, will phone authorities and order emergency response to your specific location as determined by the GPS system in the navigation unit.

The 290 horsepower from the 4.3-liter V8 engine moves through a six-speed intelligent automatic transmission to power the rear wheels. Top speed is electronically limited to 131 miles an hour. And the engine is so efficient that it has an Ultra Low Emission Vehicle (ULEV) award attached to it. That designation is normally reserved for subcompact models with tiny engines that can't get out of their own way.

As if all this weren't enough, Lexus offers a Euro-tuned suspension for superior handling, and an adjustable, self-leveling air suspension system as a comfort option. Our tester had the Euro handling package. It provided that highly desirable feeling that the tires never lose contact with the road surface.

Above all, the Lexus LS430 is a comfortable, full-luxury sedan. Inside, it has more interior volume and cargo space than the larger Mercedes-Benz S-class cars. It's all leather and wood, beautifully combined.

The leather seats are perforated, and, in hot weather, air conditioning blows through the tiny holes. Not once did I exit the Lexus with a sweat-soaked shirt. The driver's seat is simply superb, as well, providing great back support for extended times behind the wheel. In cold weather, the front and rear can be heated.

There's a power sunshade for the rear window, pull-down sunshades for the rear side windows, and two sunshades for driver and passenger. One can be swung sideways and a smaller one flipped down to the windshield.

The instruments continue the pioneering holographic display Lexus originated, and can be easily read day or night.

Headlights are high-intensity discharge units and do a fine job of illuminating the road at night without blinding oncoming drivers.

Rear-seat passengers have their own audio and air conditioning controls, in addition to reclining and massaging seats. A video system is optional and was not a part of our tested LS430.

Speaking of air conditioning, heat sensors in the Lexus know you're driving north with the sun setting in the west. It will adjust cooling airflow accordingly, sending more air to the side receiving the sun's rays. The air being re-circulated is not only filtered, but sanitized. And the air outlets oscillate once the desired temperature is reached.

The windows are all one-touch down and up. The standard moon roof is one-touch, as well.

All rear view mirrors are photochromatic, meaning you never get blasted with bright headlights from that monster SUV coming up behind you. When you back up, the rear-view mirrors tilt down to show you what you are backing into.

The tested Lexus, with all its amenities, had a final sticker price of $62,100. That makes it a bargain by any measure among luxury cars.

Don't even think of buying a base, stripped model. Get those luxury package items and enjoy your time with this remarkable car.

If you buy an optioned-out LS430, you'll be proudly driving the finest production car wisdom can buy.

I fell in love with the original Lexus LS400 that I tested back in 1989. Nothing more desirable in this price range has surfaced in 15 years.

Yeah, I'm passionate about this. Just as Lexus is relentless in improving the breed.