You know the expression "the more things change, the more they stay the same"? Well, that old cliché actually turns out to be a pretty succinct summation of the 2010 Cadillac DTS sedan.

Despite Cadillac's attempts to modernize it over the years -- including giving it the somewhat uninspiring DTS moniker back in 2006 -- this full-size flagship of GM's luxury brand remains a bit of an anachronism. Simply put, it has as much in common with the classic DeVille sedans of Detroit's golden age, an era when rolling up in one of these epic land yachts announced to the world that you'd arrived, as it does the current luxury sedan market.

While it offers its share of modern amenities, this old-school luxury liner's handsome yet conservative styling, plush ride quality and quiet, roomy passenger cabin all combine to create a leisurely motoring experience reminiscent of the DeVille's glory days. There's a big V8 engine as standard, too, though in modern DeVille/DTS fashion it sends its power to the front wheels through a four-speed automatic transmission.

In comparison, more than a few European and Japanese luxury sedans -- including the BMW 7 Series, Infiniti M56 and Lexus LS 460 -- offer fresher styling, significantly better performance and more cutting-edge gizmos. Of course, these vehicles can cost considerably more, but the DTS is also outclassed by the similarly priced Lincoln MKS EcoBoost. Further complicating matters is the fact that the new Buick LaCrosse, Hyundai Genesis and trusty Toyota Avalon offer similarly smooth rides and spacious interiors for thousands of dollars less.

In spite of all this, we still like the 2010 Cadillac DTS, and it remains a solid choice for buyers looking for a full-size American luxury sedan. But we'd still recommend test-driving several of its competitors before signing on the dotted line.

The 2010 Cadillac DTS full-size sedan is available in one well-equipped base model and three increasingly upscale trim levels dubbed Luxury, Premium and Platinum.

The standard equipment list for the entry-level DTS includes 17-inch alloy wheels, xenon headlights, front foglights, remote engine start, dual-zone automatic climate control, leather upholstery, power front seats, Bluetooth, OnStar and an eight-speaker CD stereo.

Step up to the Luxury model and you get 17-inch chromed wheels, a sunroof, front and rear parking assist and an auto-dimming driver-side mirror. Interior upgrades include a three-zone climate control system, heated and ventilated front seats, heated rear seats, a heated steering wheel, driver seat memory settings and an eight-speaker Bose audio system with a six-disc CD changer.

The Premium trim level adds a body-color grille, front seats with power lumbar adjustment and massage, a power tilt-telescoping steering column, genuine burled walnut interior accents, a heated leather- and wood-trimmed steering wheel and a DVD-based navigation system with real-time traffic updates.

Top-of-the-line Platinum models add several of the best mechanical bits from last year's Performance trim level, including a more powerful version of the base 4.6-liter V8 engine, electronic Magnetic Ride Control suspension and 18-inch wheels. Inside you'll also get a leather-trimmed dash and a classy suedelike Alcantara headliner, plus lane-departure and blind-spot warning systems.

Some of the additional features on the upper trims can be added to the lower ones as options. Other notable options include adaptive cruise control and a 40/20/40-split front bench that gives the DTS seating for six.

Under the hood, the 2010 Cadillac DTS gets one of two slightly different 4.6-liter V8s. The base engine, which comes standard on all but the top-of-the-line Platinum trim level, puts out 275 horsepower and 295 pound-feet of torque. Platinum models offer a little extra oomph courtesy of a modified V8 that makes 292 hp and 288 lb-ft of torque.

Handling the shifting chores is a somewhat dated four-speed automatic, which also gets tweaked for better performance in Platinum models. Front-wheel drive is standard.

Even with the more powerful V8, acceleration can best be described as adequate. A test car with the Platinum engine managed a 0-60-mph time of 7 seconds flat, which sounds respectable enough until you learn that most V8-powered luxury sedans -- and even a few V6-powered models -- are considerably quicker.

EPA fuel economy estimates are also just average at 15 mpg city/23 highway and 18 mpg combined for the base engine. The DTS Platinum differs with 22 mpg on the highway. However, the fact that both engines are designed to run on regular-grade gasoline does give the DTS a definite advantage over many of its competitors that demand a steady diet of pricier premium fuel.

Standard safety features include electronic stability control, antilock disc brakes, side-impact airbags for front seat passengers and side curtain airbags that cover both rows. Missing from this list are active front head restraints, something that is typically standard on a car in this price range.

As with other aspects of its performance, the big Caddy's safety ratings are merely adequate. In government crash tests, the 2010 Cadillac DTS scored five stars (out of five) for the driver and four stars for the front seat passenger in frontal impacts. Side-impact tests resulted in four stars front and rear. The DTS received a top "Good" rating in frontal-offset crash tests conducted by the Insurance Institute for Highway Safety, but a second-best "Acceptable" rating in side impact testing.

With a suspension tuned to favor a cushy ride over sporty handling, the 2010 Cadillac DTS is all about coddling its occupants. In other words, it's the epitome of a car built for comfort rather than speed.

The DTS Platinum is the best driving model thanks to its more powerful V8 under the hood and the Magnetic Ride Control suspension -- the same technology offered as an option on the Chevrolet Corvette -- that automatically adjusts suspension firmness to match road conditions and your driving style. But let's keep things in perspective here, as even with these powertrain and suspension upgrades, the DTS is no sport sedan. Also, because of its size, it can be difficult to park -- especially for shorter drivers.

Ultimately, its combination of a smooth ride and a comfortable, roomy interior make the DTS best suited to drivers who prefer to motor along at a nice relaxed pace.

Even though the DTS is roughly 18 inches shorter than some of its ancestors, its passenger cabin still feels remarkably spacious. While front bucket seats are standard, the available 40/20/40-split front bench makes this one of the few modern sedans that offers seating for six. No matter which configuration you choose, you'll find comfortable seats and abundant head- and legroom for both front and rear seat passengers. Wind and road noise are nicely subdued, creating a hushed environment that adds to the luxury sedan feel.

Out back, the huge trunk offers close to 19 cubic feet of cargo room. A pass-through opening in the middle of the rear seat makes it possible to carry long narrow items like skis with the trunk lid closed.

In general terms, the cabin offers conservative yet stylish good looks and straightforward, intuitive controls. But while most materials are much better than those used in previous generations, they still aren't quite up to par with the best interiors in the category.