Being the middle child is never easy. Just ask Jan Brady of "The Brady Bunch." Somewhat plain and not especially talented, Jan was constantly overlooked in favor of her popular older sister Marcia and oh-so-cute kid sister Cindy. Jan just couldn't catch a break, or adoration for that matter.

And so it's been for the middle child of the Cadillac family, the full-size STS luxury sport sedan that sits between the inexplicably popular DTS luxury barge and Caddy's best-selling midsize jock sibling, the CTS sport sedan. By comparison, the STS barely gets noticed, with less than half the sales of its siblings. And that's even after Cadillac made a number of cosmetic revisions last year (such as a new grille and upgraded cabin trim), while adding a beefier base V6 engine that helped bring it out of the shadows and give it more of a chance in a very competitive luxury sport sedan market. The 2009 Cadillac STS sees only minor detail changes, such as Bluetooth capability for cars not equipped with a navigation system, new wheels and a speed-limit notification feature on the navigation system.

Buyers in the luxury sport sedan segment expect the latest in high-tech gadgets, and the 2009 Cadillac STS has enough to make a Sharper Image junkie drool with delight. Among them is a lane departure warning system, which, as with rivals' systems, uses cameras to watch road lines and warn the driver if he or she wanders. There is also a side blind-zone alert system that scans for vehicles in the driver's blind spot and flashes a warning light embedded within the sideview mirrors.

We've always liked the current Cadillac STS, and last year's revisions made it even more endearing. The powerful V6 almost makes the V8 version irrelevant. Meanwhile, the STS's 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 a MB E350. Undercutting its European rivals' price tags by thousands doesn't hurt either, even if a side effect is a few mediocre-grade interior plastics.

The STS does have a new competitor this year, Hyundai's all-new Genesis sedan, which offers many of the same strong-value qualities as the STS but a more powerful V8 and a higher-quality interior. All said, know that there are plenty of excellent choices in the $45,000-$60,000 range, including this car's not-so-little sibling CTS. So, as much as we like Caddy's STS, we can't help but think that, just like Jan Brady, it's yelling "Marcia! Marcia! Marcia!"

The 2009 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 interior trim, eight-way power front seats, dual-zone automatic climate control, remote keyless entry and vehicle start, satellite radio, Bluetooth connectivity, 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 2009 Cadillac STS is a 3.6-liter V6 that produces 302 horsepower and 272 pound-feet of torque. The optional engine choice is a 4.6-liter V8 making 320 hp and 315 lb-ft of torque. Though that's certainly plenty of thrust for most folks, the truly power-hungry should know that top rivals have anywhere from 40 to 62 hp more. 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. Cadillac estimates put the V6 at 6.5 seconds to the same speed. Fuel mileage estimates range from 17 mpg city/26 mpg highway and 20 mpg combined for the V6 to 15/24/18 mpg for the V8.

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. There are also a number of available advanced technologies designed to prevent accidents, including lane-departure warning, a blind-zone alert system and active steering. The latter is available only on AWD V8 models, and is notable for turning the front wheels into a skid when the rear wheels lose traction.

In government crash tests, the STS earned four stars (out of five) for both driver and passenger in frontal tests. In federal side-impact tests, the STS scored four stars for front impacts and five stars for rear impacts. 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 2009 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 miles on the highway. Cadillac offers an optional Magnetic Ride Control 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 for 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 V6 is more than ample. With its V8-matching acceleration and higher fuel economy, the base-model STS would be our pick over the pricier V8 version.

Last year's refresh brought higher-quality wood and the addition of tasteful alloy trim to the cabin. A sportier steering wheel also debuted with more wheel-mounted controls. Fit and finish are solid, and luxury buyers should be pleased with this Cadillac's generally high-class ambience. Minor demerits include the use of some low-grade plastic trim pieces that put the STS at a disadvantage against the admittedly more costly European and Japanese luxury sedans. The overall design is also on the dull side compared to the classy confines of the CTS.

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 with 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. The trunk is also a bit small, with 13.8 cubic feet of total capacity.