The seats in all models are refreshingly supportive, for a Cadillac, without being overly firm. Arm rests and head restraints are a degree or two softer than the cushions and side bolsters, boosting the comfort factor a couple notches. All essential controls are within easy reach, although there could be more clearance between the lower door panels and seat bottom to access the front seat adjusters. For this reason, we were especially grateful for the seat memory feature, which often saved us from having to reach down there. The interior is noticeably roomier than that of the marginally smaller CTS.

Instruments are easily scanned, white-on-black round analog gauges, with a large nested tachometer and speedometer between the smaller fuel and engine temperature gauges. The speedometer changes between English and metric electronically, so there's only one set of numbers around its circumference.

Cruise control and running lights are managed via a stalk on the left side of the steering column, windshield wipers and washers with a stalk on the right. Buttons in the steering wheel spokes provide redundant controls for audio and driver information functions. The steering wheel hub has been re-shaped for 2008; it now looks more substantial, even a bit futuristic, but not all that different from before. The available head-up display projects speed and other key information onto the windshield, so that the driver does not need to look down at the gauges.

The available Bose 5.1 stereo incorporates one of the industry's first OEM-installed surround-sound systems. Fifteen Bose speakers do the job, plus an integrated six-disc CD/DVD changer that plays DVD-A, CD, and MP3 formats. The setup also includes an eight-inch VGA-quality touch screen and advanced navigation, Bluetooth phone capability, and OnStar with advanced voice recognition. A word of caution, however: the top-level stereo system, although delivering superb surround-sound, is multi-tasked with a navigation system that, in combination, demands an extensive study of the owner's manual to operate with any degree of alacrity and confidence.

The 2008 OnStar system features a fully integrated GPS navigation setup called Turn-by-Turn Navigation. Turn-by-Turn allows drivers to talk to a live advisor, who can download complete step-by-step directions to the vehicle through the OnStar system. These audio directions then automatically play through the vehicle's stereo as needed (after the OnStar operator hangs up), triggered by the system's GPS capabilities. This enables drivers to be led to their destination while keeping their hands on the wheel and eyes on the road.

Storage cubbies include map pockets in all four doors. The front center console is deep and wide and pre-wired for cellular and Bluetooth (to wirelessly tie a cell phone into the car's audio system, allowing hand-free operation). The glove box, though, is barely sufficient to hold the navigation DVD case and owner's manual. Two cup holders are provided front and rear. The trunk is fully lined, with articulated, gas-pressurized struts.

Fit and finish are top grade, with notably tight trim tolerances. Careful attention was paid to reducing noise, vibration and harshness, with remarkable and commendable success. Specially laminated windshield and front door glass, wind tunnel-tuned outside mirrors and high-density/low-mass sound-deadening padding make this a quiet car even by Cadillac standards.

The Platinum Edition features hand-cut and hand-sewn leather on the instrument panel, door trim and center console areas. The steering wheel is heated. The seats are fully covered with a semi-aniline leather called Tuscany. Wood trim is an olive ash burl stained a saddle shade. Chrome accents highlight the instrument panel and doors. Even the floor mats are upgraded, and there are Platinum badges on the door sills. Only two interior colors are offered: Cocoa over Cashmere or all-Ebony.