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2006 STS

Overall rating:  Product Rating: 4.0

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STS: what difference do all-wheel-drive and the sport suspension make?

by mkaresh:      Jan 19, 2006 - Updated Dec 16, 2006

Product Rating: 3.0 Recommended: Yes 

Pros: Acceleration, closest Detroit has yet come to a premium German sedan
Cons: Styling less bold and handling less entertaining than should be; rear seat
The Bottom Line: Very good, and certainly worth a test drive, but should be better still.

Last year I reviewed the 2005 Cadillac STS V8 with the standard suspension, steering, and 17-inch wheels because the dealer did not have a car with the sport suspension and 18-inch wheels at the time.

I returned to the Cadillac dealer this year to check out the new DTS, and while there took the STS with the 1SG package (which includes a ZF steering system and sport suspension) and all-wheel-drive for a spin.

So, do the stiffer suspension and lower profile tires make the STS into a genuine sport sedan worthy of competing with the likes of BMW and Infiniti?


The STS looks much like a stretched CTS with edges smoothed off and most of the smaller sedan’s many creases ironed out. Unfortunately, adding those inches and taking away those edges and creases results it a much less interesting design. In the most evident change from the CTS, the front and rear lamps don't kink into the fenders on the STS. As a result the car's corners have the overly square, drab, somehow Stalinist look.

The 18-inch wheels substantially improve the car's overall appearance, especially around the rear fender whose huge opening makes the standard 17s look tiny.

I must admit that the STS with the 18s does catch my eye from time to time. It is a handsome car, with a mild amount of edginess to it courtesy of the modestly raked beltline and sharply creased fenders. But it could have been better looking still.

Certainly far fewer people will dislike the styling of the STS than have disliked that of the CTS. But also far fewer will love it. People noticed the CTS. A real disappointment for me.

Inside Cadillac has similarly taken far fewer stylistic chances with the STS than with the CTS and SRX. The instrument and door panels are thoroughly conventional. The materials are generally appropriate for a $50,000 car. The main exception is the use of hard plastic on the center console. For hard plastic it looks and feels high in quality, but you touch it all the time and will never mistake it for anything but hard plastic. I’ve been similarly let down by the relatively pedestrian ambiance of the current E-Class interior. To me, the interior of the Lexus LS 430 looks and feels far richer than either. Cadillac benchmarked the wrong target in this area.


The driving position is very good, neither too low nor too high relative to the instrument panel. The pillars and header do not overly intrude. The wheel has power adjustments for tilt and telescope. One nit: the power tilt is very quick, so small adjustments can be difficult. Why? At the very least this problem should have been fixed for 2006.

The front seats are reasonably comfortable, but lack the instantly evident outstanding comfort of those in the big Lexus and the Swedish flagships. They are a bit on the firm side, perhaps in an attempt to out-German the Germans, and overly flat. For aggressive drivers lateral support is deficient, except possibly for those especially broad of beam.

The rear seat is another major disappointment. The STS is larger and more expensive than the CTS, but its rear seat is only marginally better. While headroom is ample, knee room behind the front seats and toe room beneath them are both in short supply. Adult men will fit, but with little room to spare. And they won’t be comfortable, as the cushion is too low to the floor to provide thigh support.

The trunk is about average in size for this class of car. But be aware that—unlike in the CTS, E-Class, and 5-Series—a folding rear seat is not available.

On the Road

The predominate impression I took from last year's test drive was of thorough refinement. That STS glided smoothly, almost liquidly over just about any pavement, at any reasonable speed. I drove the car over stretches of rough pavement that produce much thumping and jostling in the average car. They were barely heard or felt in the STS. Noise levels even at 90 miles per hour remained low.

And this is not simply the product of a very soft suspension. The STS’ standard suspension remained composed over the rough stuff. This was perhaps the most impressive aspect of the car.

The sport suspension lacks this fine balance between ride and handling. Handling is more responsive, and cornering is flatter. The car feel tauter, almost German (the all-wheel-drive system also plays a role here). But the ride is also substantially busier, with much more abrupt (if not quite harsh) reactions to bumps and potholes. Some people will willingly make this trade off, but it is most definitely a trade off.

The sport suspension includes GM's ultra-quick magnetically-controlled shocks. In this application they don't seem to help the ride much, though handling definitely benefits. The firmness of this suspension can be altered through the car's information center. Or so I've read. Despite searching for at least ten minutes, I could not find this adjustment. Most likely the suspension was set to "normal," but it could have been in a Sport setting the whole time.

Noise levels were higher this time around, courtesy of performance tires that thumped over patchy pavement. The DTS I drove the same day was noticeably quieter.

The engine remains the same, and thus remains considerably more refined than past Northstar V8s. At idle it is nearly silent, and even at full throttle the noise level remains moderate. Well, my father again called it “loud,” but this was only relative to the otherwise near silence of the car. Earlier Northstar V8s sounded too similar to traditional, less sophisticated American V8s for my taste. This third-generation unit still has a lower engine note than the typical import V8, but the overall sound is just as refined. It now sounds like the DOHC V8 it is. The noise you do hear you’ll enjoy hearing. Unless you're my father, who preferred the quieter application in the DTS.

The Northstar V8 has always been powerful. That said, I was unimpressed by the power delivery of first and second generation units. They felt soft to me until the tach hit 4,000 or so, where they took off with a roar. There was an obvious source of this issue: GM had decided not to gift the engine with variable valve timing to minimize cost and complexity. They reasoned that a few hundred more cubic centimeters than competing V8s would more than compensate.

Well, peak power is one thing, the shape of the torque curve another. If it has a plumper torque curve, a 150-horsepower engine can feel thrustier around town than a 300-horsepower engine.

With the latest redesign of the Northstar GM finally bit the bullet and included variable valve timing. Though the specs suggest little improvement—the torque curve still peaks at a moderately lofty (for this size engine) 4400 RPM—the revised engine’s midrange feels significantly plumper.

It helps that the engine is finally paired with a five-speed automatic (and a six-speed is on the way). GM made do with a four-speed transmission for far too long, and the widely-spaced ratios of that transmission were not a good fit with the Northstar engine.

Even with the extra weight of the all-wheel-drive system the STS V8 remains a very quick car. All-wheel-drive helps transfer all of the Northstar's power to the pavement with no drama. It is especially helpful when accelerating out of turns. Where a rear-drive car would be inclined to spin a tire or oversteer, the all-wheel-drive simply pulls.

The all-wheel-drive car has a distinctly different feel when you get on the gas, especially at low speeds. More mechanical and tied-down--more German, if you will--but also more massive. You can feel those extra bits of machinery exerting drag through the seat of your pants. It's as if the transmission were a gear lower than it actually is. Some people will like this feel, others will not.

And what about my main issue with the STS last year, its uncommunicative steering? The ZF system is an improvement, but still does not challenge those in BMW sedans--even though ZF also supplies many (all?) of these. Effort is higher, likely because of the all-wheel-drive system as well as the different tuning, and weighting is more natural, but the response remains a bit slow for my taste and the level of communication remains lacking.

Cadillac STS Price Comparisons and Pricing

The two most popular comparisons (base to base, without rebates, adjusted for feature differences):

Infiniti M35: about $1,000 less at MSRP, $1,100 less at invoice compared to the STS V6

CTS 3.6: about $5,300 less at MSRP, $4,700 less at invoice

Prices change frequently, and differences will vary based on feature level. To quickly generate these and other comparisons with the specific features you want, visit my Web site, www.truedelta.com. (It's the only site that provides true "apples-to-apples" price comparisons.)

TrueDelta's page for the STS:


Last Words

The STS remains a very solid car, and the sport suspension and steering do increase its sportiness. Despite the penalty in ride quality, I'd personally want them. My father, on the other hand, would not.

My issues with the STS continue to concern areas where the car is only acceptable for the class instead of being outstanding. Plenty about this car is very good, but nothing about this car is “must have.” If the average E-Class or 5-Series owner was forced into an STS they would likely not be disappointed. But I don’t see this car bringing those owners on their own accord into Cadillac showrooms.

Until Cadillac upgrades the seats and interior ambiance, I’d steer luxury sedan buyers towards the Lexus LS 430 (which doesn’t drive badly when equipped with the optional sport suspension) or even Cadillac's own DTS (which my father preferred, much to my surprise). Until GM upgrades the steering, I’d steer sport sedan buyers towards the BMW 550i. Especially if they want a manual transmission, which the Cadillac does not offer.

I don't mean to imply that the STS is a bad choice. It's just not the best choice.

A Note on Cadillac STS Reliability

I cannot practically cover reliability within the context of this review. However, many people are interested in such information, so I've started collecting my own data. Results, once they are available, will be posted to my site, www.truedelta.com, with updates every three months.

Unlike other sources, TrueDelta will clearly identify what difference it will make if you buy an STS rather than another vehicle by providing "times in the shop" and "days in the shop" stats (among others). You will be able to specify the number of years, annual miles, and types of repairs to include in Cadillac STS reliability comparisons.

Before I can report results, I need data on all cars--not just the STS--from people like you. To encourage participation, those who help provide the data will receive free access to the site's reliability information. For non-participants, this access will cost $24.95.

For the details, and to sign up, visit www.truedelta.com.

A link to this website and alphabetized links to my other vehicle reviews can be found on my profile page.

If you're an Epinions member, and you want to receive an email alert from Epinions when I post a new review, click here.

Some of my reviews of related vehicles:
2005 Cadillac STS V8 review (2005 with base suspension)
BMW 5-Series review
Cadillac CTS review
Cadillac DTS review
Chrysler 300 review
Infiniti M35 review
Jaguar S-Type review
Lexus GS 300 review and Lexus GS 430 review
Lexus LS 460 review
Mercedes E500 review
Saab 9-5 review
Volvo S80 review
Product Rating: 3.0
Recommended: Yes 

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