The new Cadillac DeVille still is one of the two largest passenger cars sold in the United States and it's still very much an American luxo-barge in the grand tradition.

But when Cadillac tells you its big traditionalist is new and improved, you'd better believe it.

Although it maintains all the upscale den-on-wheels interior, it also represents an extraordinary level of dynamic competence for a car in its class. It makes the rock, roll and wallow of the previous DeVille look distinctly bovine, and it also proves that agility and relaxed, roomy comfort don't have to be mutually exclusive.

It also adds a high-tech safety innovation that's particularly significant considering the older buyers who are most likely to sign up for a DeVille. As the years go by, one's eyes tend to be less effective after dark. Cadillac's new infrared-based night vision system is designed to compensate for that natural frailty, giving the driver a hint of what's beyond the range of the headlights.

Size really matters

First, let's take a closer look at the big picture.

Big is a word that applies here. At almost 17.3 feet and two tons, the DeVille's specifications straddle sport-utility territory. Nevertheless, this is a tidier package than its predecessor. The wheelbase is 1.6 inches longer, helpful in the ride-quality department, but overall length has been reduced 2.6 inches and width has shrunk by 2 inches.

Thanks to a slightly higher roof line -- it's taller by about a half-inch -- and improved packaging, the DeVille's interior volume is essentially unaffected by the body shrinkage. Rear seat volume has been reduced by about 1 cubic foot, but there's plenty of move-around space, and the DeVille still offers the roomiest interior in its class.

More important is this new car's structure. The latest DeVille shares the same chassis as the Seville, a much stiffer platform than the previous generation. As I never tire of saying, a stiff chassis is the key to good handling because the suspension components don't have to compensate for chassis flex in addition to their other duties.

In the case of the DeVilles in general -- and my DTS tester in particular -- these are some pretty special suspension components. We've talked about Cadillac's advanced stability systems on other occasions -- continuously variable road sensing suspension (CVRSS) and StabiliTrak.

CVRSS essentially is an active-handling system, designed to adapt suspension settings to what's going on underfoot. StabiliTrak is conceived to intervene to restore stability when the car's computer concludes that the car isn't doing what its driver wants.

The latest DeVille has a new shock absorber that's capable of much quicker adjustment in its damping rates than those previously used, and the system can make adjustments selectively. That is, the left front shock can be extra-firm during a hard right-hand turn, while the right rear ca n adjust simultaneously to keep that tire in contact with the pavement.

The result is a significant reduction in body roll during quick maneuvers, such as the kind you might make in avoiding one of our antlered friends out there somewhere.

Combined with one of the better iterations of GM's steering systems -- nicely weighted, with a surprisingly good sense of where the front wheels are pointed -- the DeVille DTS delivers handling responses that wouldn't be out of place in a European sedan with a fancier pedigree and significantly higher price tag.

300 horsepower

Another element of the DeVille's performance that's been improved is what happens when the driver mashes the gas pedal against the floor.

I'm not talking about power per se.

Though GM has been refining the 4.6-liter Northstar V8 to smooth its operation even further, improve fuel economy (by 2 m.p.g. on the highway), and also to improve its emissions performance, the engine's pow output is unchanged: 300 horsepower (275 in the basic DeVille and DeVille DHS, for High Luxury Sedan, replacing the former d'Elegance).

Cadillac figured 300 horsepower was plenty, and I agree. Although its curb weights are essentially unchanged, this baby can honk when the light turns green.

The change lies in the dynamics of power delivery, specifically, the absence of torque steer. Torque steer describes a tendency for the front wheels to pull the car to one side or the other during hard acceleration.

OK, let's see what we're looking at after dark, that is, the night vision issue.

A grille-mounted camera peers down the road, gathering infrared energy. The system then projects a holographic image that appears to be floating just beyond the windshield. The image can be adjusted for brightness andmoved around.

I'll admit it probably takes some practice with this system to derive real benefit from it. It seems to require a certain level of interpretation on the part of its user.

I guess what I'm sneaking up on is that I didn't find night vision helpful. For one thing, I find the system more of a distraction than anything else. Seeing greenish images moving around just beyond the steering wheel makes the eye want to check them out, which means you're no longer looking down the road.

I'm just not sure it's ready for prime time yet. And I am sure I wouldn't spend the extra two grand to have it.

The DeVille's electronic warning inventory includes a proximity alert system for backing up. Called Ultrasonic Rear Parking Assist, it beeps to let you know when you're about to flatten something or, worse, someone.

Similar to most cars in this class, the DeVille has air bags all over the place inside, and its new architecture should lend an extra measure of protection for the driver who manages to put the car on its roof. A very good antilock braking system is standard, and so is traction control.

The styling ...well, Cadillac calls the new DeVille "trimmer, sleeker and more cosmopolitan."

I don't know. It looks to me as though someone punched it in the face, and I think the Lincoln Town Car holds the edge in this one area.

But this is a pretty capable car, and it's far less expensive than an Audi A8, BMW 7-Series, or Mercedes S-Type.

For all its impressive merits, the DeVille really belongs to a class of two. The other member is the Town Car.

And in that narrow class, this new Caddy is clearly top dog.

Rating: 4 Stars

Vehicle type: Front-engine, front-drive, full-size luxury sedan

Key competitor: Lincoln Town Car

Base price: $45,370

As tested: $51,735

Standard equipment: ABS, Stabilitrak, traction control, side air bags, automatic climate control, AM-FM-CD-cassette audio, heated power leather seats, heated rear seats, power windows, power locks, heated power mirrors, electroch romic rearview mirror, power tilt-telescope steering, aluminum alloy wheels

Specifications

(Manufacturer's data)

Engine 300-hp 4.6-liter V-8

EPA fuel econ. 17 m.p.g. city

28 hwy.

Curb weight 4,047 pounds

Wheelbase 115.4 inches

Length 207.2 inches

Width 74.5 inches

Height 56.7 inches

Assembled in Hamtramck