Cars.comparison: Luxury Performance Sedans

OK, so you want it all — a luxury car with features and amenities that pamper you, but one that can also carve through corners when the mood strikes. With that in mind, we've tested three six-cylinder sedans to see which has the goods to best meet your needs.

 = Category winner
The Contenders
2008 BMW 528i2008 Cadillac STS V-62007 Infiniti M35 Sport
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Base MSRP
$44,300$42,390$44,250
Price as tested
$52,020$56,530$51,940
Drivetrain
BMW puts some thrilling engines in the 5 Series. This isn't one of them — it has substantially less horsepower than the other contestants and even less torque. For the price, the others give the 528i a sound thrashing. The fact that you can get a stick shift seems the sole advantage. The new direct-injection V-6 makes a healthy 302 hp; it's strong enough to make you forget about the optional V-8, and the six-speed automatic gives up nothing to the others.We love the M45's stout V-8, but the more practical M35's V-6 didn't let us down and should be enough power for most buyers. The five-speed automatic's shift quality is heavenly.
Gas mileage* (city/highway, mpg)
18/2717/2616/23
Ride and handling
With the most balanced weight distribution, the 528i has BMW's storied handling, but the meager torque makes this car less entertaining than the M35 on twisty roads. BMW no longer runs away with this contest.Overly light steering diminishes the STS' sporting ambitions. It's also the biggest car of the three, and you feel its size; it's better suited to a long highway cruise than your favorite winding road. The M35 Sport's suspension tuning is especially taut, but the sedan excels at cornering. Steering response is precise and direct, though Infiniti could dial back the power assist and we'd like it even more.
Country club cred
Birdie: The 5 Series' styling has grown on us. It will have no trouble getting respect at the club, but next to the STS it looks too timid. Eagle: Big and bold, the STS' new grille commands attention, and the sedan's creased looks set it apart. Par: The M's lines are handsome, for sure, but it blends into the crowd of high-end metal that is the members-only parking lot.
Comfort and roominess
The front seats are as good as ever, and passengers loved them, too. Backseat headroom is the highest, but unfortunately the 5 Series has the least legroom of the three. The front seats are supportive and not overly firm, but even though rear-seat measurements are larger than those in the M35, the backseat in the STS feels smaller. An excellent driving position and comfortable front seats result in fatigue-free driving. Backseat room is adequate for adults.
Interior design and quality
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Despite some changes, the 5's interior rides the line between austere and boring. The high-quality materials are appreciated, but some people dislike the steering wheel and ergonomics.
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After soaking in the kickin' new exterior, the modestly updated cabin is a letdown; it doesn't keep pace with the competition. If only the STS had the new interior from the CTS, maybe things would be different.
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The M35 Sport has an aluminum-trimmed interior in place of the equally modern base version's real wood trim. With each interior, there's just the right amount of metal or wood.
High-tech features
The 528i is spilling over with available gadgetry: Active steering, active cruise control, lane departure warning, night vision. You even get things you may not want, like the iDrive control system and the wonky new gear selector. The STS has a blind spot warning option in addition to lane departure warning, and its Magnetic Ride Control and head-up display are intriguing features. However, the touch-screen interface can't make up for the navigation system's terrible menus, and a backup camera is MIA. The M was early to market with useful features like lane departure warning, a backup camera and keyless ignition, but the other guys have caught up. Rear Active Steer remains unique, and the backrest-mounted surround speakers have independent level controls that some multichannel stereos lack.
IIHS crash-test performance
Like the STS and M35, the 5 Series received a Good rating for frontal-offset crash-test performance, but its Marginal rating for the side-impact test puts it at the bottom in this group. With scores of Good for the frontal-offset crash test and Acceptable for the side test, the STS is in the middle of the pack here. Top overall scores of Good in the frontal-offset and side-impact crash tests give the M35 the win.
Utility and cargo room (cu. ft.)
14: It doesn't offer the most space, but the 5 Series is the only one that can have a split-folding backseat to expand the cargo area. 13.8: The STS only offers a pass-thru for carrying long, skinny items in the cabin. 14.9: The M35's trunk is the largest of the three, but like the STS, the Infiniti only has a pass-thru.
Overall value
No one would ever accuse BMW of being a value leader, but the 5 Series competes well when not equipped with lots of extras. Good luck finding one not equipped with lots of extras. The STS has the lowest base price, but $2,000 is relatively small change in this category and would have been well spent on the interior. Like many Infinitis, the well-equipped M35 hits the sweet spot for what you get for your money.
 
Editors' choice
The 5 Series went from clobbering all of its competition to merely edging them out, and now it's falling behind in some ways. Electronic bungles like iDrive continue to hurt the brand, and performance features like active steering have failed to inspire enthusiasts. The side-impact crash-test rating is a nail in the 528i's coffin.The more aggressive face and new engine score points, but we're looking for an all-conquering car. The STS doesn't deliver when the road begins to bend, and its interior needs more updating. If you're looking for well-rounded, this is it. The combination of drivability, luxury accommodations and useful technology is a winner. Throw in the best crash-test ratings and the M35's above-average reliability, and this one's in the bag.
*To allow comparison between 2008- and 2007-model-year sedans, all gas mileage estimates shown are based on the EPA's new fuel economy testing procedures that went into effect with 2008 models.
Posted on 9/26/07
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