"Marcia, Marcia, Marcia!" is the familiar whining call of poor middle child Jan Brady, constantly overlooked in favor of her popular older sister Marcia and cute-as-a-button younger sister Cindy. Life just wasn't fair for Jan, and it hasn't been much rosier for Cadillac's middle-child sedan either. The 2008 Cadillac STS slots in between the inexplicably top-selling DTS land yacht sedan and the sporty midsize CTS that has received tons of attention since its debut. And with that car receiving a complete overhaul this year that will surely raise its popularity even more, you can almost hear the STS growl, "CTS, CTS, CTS!"

To keep pace with its more attention-grabbing sibling (as well as other larger luxury sport sedans), the 2008 Cadillac STS has been revised inside and out. It's sort of like Jan ditching her dorky glasses. The wide, two-level egg-crate grille is particularly striking, and the improved cabin trim is bound to get the attention of full-size luxury car shoppers. Most significant is a new base engine, a 3.6-liter V6 engine that increases power by 47 horses and 20 pound-feet of torque compared to last year's six-cylinder. This power plant, now featuring direct fuel injection, not only puts more guts to the pavement, it's also more fuel-efficient and has reduced emissions. It's hard to argue with that formula, and considering that the STS V6 is basically as quick as the unchanged STS V8, we'd have no problem recommending saving a few bucks by going with the base engine.

Technology is now the name of the game when competing against big guns like the Audi A6, BMW 5 Series, Infiniti M35/45 and Mercedes-Benz E-Class, and the 2008 STS adds several high-tech optional features to its repertoire to keep up with the Joneses. The Lane Departure Warning System works like other brands' similar technologies, utilizing cameras in the rearview mirrors to read road lines and then alert the driver if he starts to stray with visual and audible signals. A Side Blind Zone Alert System scans for vehicles in the driver's blind spot and flashes an amber light in the rearview mirrors. Some drivers may find these "nanny technologies" irritating, but with so many in-car driver distractions nowadays, it's hard to deny their usefulness.

We've always liked the current STS, and the revised 2008 edition makes it even more endearing. The powerful new V6 almost makes the V8 irrelevant and boasts more power than the engines in the BMW 528i and 535i, as well as the Benz E350. Meanwhile, the STS' ride and handling continues to impress with moves that almost make you forget you're driving a sedan that's 6 inches longer and 200 pounds heavier than an E350. Having a price that undercuts the competition by thousands doesn't hurt either, even if a side effect is a few low-grade interior plastics. The 2008 Cadillac STS may never meet the DTS' sales figures or the CTS' attention, but at least it's got more going for it than Jan Brady.

The 2008 Cadillac STS is a large luxury sport sedan available in V6 and V8 models. Both versions feature 17-inch wheels, leather seating, wood and alloy-look interior trim, eight-way power front seats, dual-zone automatic climate control, remote keyless entry and vehicle start, satellite radio, an eight-speaker Bose sound system and OnStar. The V8 version adds a CD changer, memory seating presets, heated seats (front and rear), a heated steering wheel and rain-sensing wipers. Many of the V8's features can be added to the V6 model via a series of packages.

Other features available on both models (in packages or as à la carte items) include a sunroof, xenon headlamps with washers, adaptive cruise control, a lane departure warning system, a blind spot warning system, a head-up display, and heated and ventilated front seats. The navigation system is bundled with a Bose surround-sound audio system. There is also the Performance Handling Package, which adds better wheels, tires and brakes. An adaptive suspension system (Magnetic Ride Control) is also available, as are larger 18-inch wheels.

The standard engine on the 2008 Cadillac STS is a 3.6-liter V6 that produces 302 horsepower and 272 lb-ft of torque. Despite a significant increase in horsepower for 2008, fuel efficiency has improved and tailpipe emissions have been reduced. The optional engine choice is a 4.6-liter V8 making 320 hp and 315 lb-ft of torque. Both engines come only with a six-speed automatic transmission, and both can be ordered in rear-wheel-drive or all-wheel-drive guise. In performance testing, the STS V8 reached 60 mph in 6.3 seconds. Considering that the new V6 accelerates with similar gusto and turns in better fuel mileage, it's hard to justify the V8's added price and weight.

Antilock disc brakes, stability control and a full complement of airbags are standard on every Cadillac STS. The airbags include front-seat side and full-length side curtains. For 2008, there are a variety of advanced technologies designed to prevent accidents, including lane departure warning, a blind zone alert system and active steering. The latter is available only on all-wheel-drive V8 models, and is notable for turning the front wheels into a skid when rear wheels lose traction. In Insurance Institute for Highway Safety frontal-offset crash testing, the STS scored a rating of "Good," the highest possible. It scored a second-best rating of "Acceptable" for side-impact protection.

Although large in size, the 2008 Cadillac STS sedan feels three-fourths its size when driven with enthusiasm, yet it rides like a supple luxury car when you're gobbling up the miles on the highway. Cadillac offers an optional Magnetic Ride suspension that includes Touring and Sport modes. In Touring mode the Cadillac STS provides a cushy ride and composed handling, although the car will still dive into the turns with unwavering composure and never feels as if it's sprung too softly. In the Performance setting, the handling is a little sharper and the ride a bit stiffer, but the STS handles so well in Touring that we question the necessity of the two settings. Braking is strong as well, with progressive pedal action and an impressively short 120-foot stopping distance from 60 mph. The torquey new V6 is much better than the engine it replaces. With its V8-matching acceleration and higher fuel economy, the base-model STS would now be our pick over the pricier V8 version.

Cadillac snazzed up the STS interior significantly for 2008 with higher-quality wood and the addition of tasteful alloy trim. A sporty new steering wheel looks and feels better, while more wheel-mounted controls have been added. The good fit and finish remains and luxury buyers should be pleased with this Cadillac's generally high-class ambience. There are some demerits, though, mostly having to do with some low-grade plastic trim pieces that put the STS at a disadvantage against the top European and Japanese luxury sedans. Controls are straightforward and easy to use, with the exception of the confounding memory-setting procedure for the driver seat, mirrors, radio and climate controls. Unlike traditional systems, which place buttons on the door or driver seat, you must dive deep into the navigation touchscreen to set memory functions. It's frustrating and unnecessarily complicated, but at least it's something done only occasionally.