Cadillacs of the 20th century were known for length and opulence, earning the less-than-complimentary “luxobarge” moniker. But a new century gave General Motors’ luxury division an opportunity to take on the Mercedes-Benz E-Class and BMW 5 Series. In 2005, Cadillac launched the STS, a sleek and stylish sedan with European DNA and American muscle under the hood.
Based on an Opel (a German automaker owned at the time by GM) platform, the STS (Seville Touring Sedan) brought a new level of refinement to the Cadillac’s lineup. Available power included GM’s Northstar V8, the company’s most sophisticated engine to date.
Seeking to keep up with Germany’s best, Cadillac ensured the STS had state-of-the-art technology, like adaptive cruise control, lane departure warning, and night vision. That may seem ordinary today, but this was almost 20 years ago. The STS also had the distinction of being the first Cadillac with all-wheel drive (an option over the standard rear-wheel-drive setup).
When the STS first hit the streets in 2004, I recall thinking that an American automaker may finally have a chance at succeeding in the luxury sedan game. But the idea of a Mercedes- or BMW-killer was short-lived as the STS was a victim of bad timing.
Just as this Cadillac gained traction, General Motors filed for bankruptcy in 2009. As a result, the company re-evaluated numerous product lines, and the STS was assigned to the history books after 2011.
Although it’s been a dozen years since a Cadillac dealer sold a new STS, this sedan still sees action in the used car market. They’re cheap, luxurious, and reasonably powerful by today’s standards, all desirable characteristics for some buyers. Yet, rushing out and buying any STS could be a mistake. There’s a clear difference regarding reliability between the different model years.
An analysis of engine reliability data from FIXD sensors installed in Cadillac STS models shows a sharp dividing line between the best and worst years. It will surprise no one that the oldest examples are the ones to avoid. Keep reading, and I’ll tell you how we came to this conclusion.
But the FIXD Reliability Score (which measures engine reliability information from FIXD sensors) isn’t the sole measure for giving these Caddys a thumbs up or down. I also looked at other critical factors: safety, fuel economy, maintenance costs, and market value. Another calculation is incorporated into my thought process: F.I.R.I.S. (FIXD Internet Review Index Score). I’ll explain the details later, but F.I.R.I.S. captures insights from professional car reviewers and owners.
Add all these factors together, and here’s an overview of the results.
Cadillac STS Engine Reliability Score, Safety Ratings, MPG, Value v.s. Value for the Money, and F.I.R.I.S. – Year by Year
The findings for the best and worst Cadillac STS years are based on:
- FIXD Reliability Scores (engine reliability)
- National Highway Transportation Safety Administration (NHTSA) safety ratings
- Environmental Protection Agency (EPA) fuel economy estimates
- Kelley Blue Book (KBB) market value compared to yearly upkeep costs (based on RepairPal.com data).
- F.I.R.I.S. rankings (a summary of online ratings and reviews)
There are many ways to assess vehicle reliability. To me, this starts with engine dependability because if what’s under the hood doesn’t work, why bother with that car? After all, people just want a vehicle that starts and gets them where they need to go.
Fortunately, FIXD sensor data provides a unique insight into engine reliability. I didn’t have to guess or rely on conjecture before assigning a best or worst label to each STS model year. At the same time, I understand that older cars are less likely to have flawless powerplants. This helps set expectations and determine a bare minimum FIXD Reliability Score for an STS to pass muster.
What are these thresholds? Ideally, a score of 5 or 6 (out of 10) for engine reliability is needed. Yet, sometimes, this just isn’t possible, which sets 3 as the floor for an STS to be a worthwhile purchase. However, not every STS with a FIXD Reliability Score of 3 is a buy. Later, we’ll explain why you want to avoid the 2007 model year.
Although engine reliability is a significant influencer in judging the Cadillac STS, I didn’t keep my blinders on. Other factors played a part in these decisions. Specifically, looking at safety, fuel economy, and value can help tip the balance. For instance, I was on the fence about the 2009 and 2011 model years, but solid safety scores and decent fuel economy pushed these into the best-years column.
Regardless of the manufacturer, I also take a dim view of the first year of a new model or generation. History shows that automakers have a knack for turning pioneering customers into beta testers. These early editions tend to have gremlins, bugs, and other nagging issues that often get resolved in subsequent years. In other words, the manufacturer rushed a car into production or failed to engineer and test their offering more thoroughly. I find it best to play it safe by avoiding a debut model year.
If you’re in the market for a car, take a look at our article on the USA’s most reliable and cheapest to repair cars in the U.S. Don’t get stuck with a lemon; use our data to help you shop.
Engine Reliability Score – Over The Years
Fluctuating FIXD Reliability Scores is nothing unusual for older cars like the Cadillac STS. Sensor data captures how often check engine lights occur in Cadillac STS models with the FIXD device. Top achievers receive 10, while 1 is as bad as it gets (5 is average).
The 2010 model year is at the head of the class with a 6. This result is mediocre from a broader perspective but is a top result in the world of the STS. Unfortunately, the other editions don’t get any better than 3. And it’s even worse for the 2005, 2006, and 2008 model years (take a wild guess which side of the best-worst line they got assigned to).
It all adds to a Cadillac that gets many check engine lights, which only repair shop owners like to see. Yet, it’s helpful to know that not every dashboard warning light is an automotive death sentence. Often, a dying battery, loose gas cap, or a cracked hose is the cause of the trouble, which can be a relief for an owner.
Read the Cadillac STS Check Engine Light article to learn the most common causes of check engine lights in this vehicle.
NHTSA Safety Score – Over The Years
One thing can be said about the STS: it does very well in government crash tests. A 4.0 (out of 5) is commendable, and this Cadillac exceeds expectations. Most years get a praiseworthy 4.5, and the last STS (2011) aces NHTSA’s evaluation with a perfect 5. At least STS shoppers can check the safety box among a list of must-have features.
No crash test information exists for the 2005 and 2006 model years, but this isn’t unusual. Sometimes, it takes a while for a new model to go through the rounds at NHTSA. I wouldn’t worry about this, as you’ll discover other reasons for avoiding these editions of the STS.
Did you know that buying a safer vehicle helps keep insurance rates low?
If you live in one of the states listed below, we can show you the cheapest vehicles to insure in yours.
|What Used Cars Are the Cheapest To Insure In:|
MPG – Over The Years
While fuel economy has been a concern for 50 years, it was never a priority for those buying the STS when new. A big car and a big engine equals, at best, mediocre fuel economy. However, second-hand buyers are likely to be more focused on fuel economy thanks to a tighter budget and gas being more than three dollars a gallon.
In truth, you could do much worse than an STS for avoiding the pump; 18-19 miles per gallon is far better than a guzzling SUV from the same era. Even more impressive is that the 2011 STS gets an average of 21 MPG.
These ratings are average for the respective model years and combine what’s under the hood—the STS came with V6 and V8 engine options. So, you’ll want to focus on examples with a V6 if fuel sipping is the goal.
Current Market Value of All Cadillac STS Years vs. Value for the Money
Excessive repair and maintenance costs can drag down a car’s value; we don’t see this with the Cadillac STS. Some of this is due to the STS being old and already getting hit with depreciation. In other words, an older vehicle’s value (one that’s still running) can only drop so far.
At the same time, despite the STS’s age, each newer model year is accompanied by an increase in market value (green), according to Kelley Blue Book (KBB). This is precisely how the numbers should show and can at least partially due to the STS being inexpensive to keep on the road. Surprisingly, RepairPal data shows that the average STS owner has yearly maintenance and repair costs of $553. That’s about the same for a Toyota Camry.
A look at averages can sometimes mask outlying years with high upkeep costs, but this doesn’t exist with the STS. No individual year exceeded the average by more than 15%. The costliest to maintain is the 2009 STS, with owners spending $646 annually.
When shopping for a used (make) (model), it’s important to keep in mind that not all vehicles are cared for equally. To protect yourself from lemons, take along a FIXD Sensor on your test drive. FIXD connects to a free app on your smartphone to tell you more about the vehicle you’re checking out, including check engine lights and other hidden issues that the owner or dealership may be attempting to hide. Click here to learn more and get FIXD for only $19.99 (regular price $59)!
F.I.R.I.S. – FIXD Internet Review Index Score– Over the Model Years
F.I.R.I.S. sounds more complicated than it is. We compile year-specific model ratings from four trusted automotive sites: Cars.com, Edmunds, KBB, and CarGurus. These scores are then averaged and recalculated on a scale of 1-10. Centralizing this information brings together varying viewpoints in an easy-to-understand format.
The F.I.R.I.S. score shows that professional reviews and owners think highly of the Cadillac STS. Among all years, the car averages a 9.1 (that’s an A-), which is notable. Meanwhile, the 2010 model year is a straight-A student, receiving a 9.4. The low end is still high, with the 2007 and 2009 STS ranking a still-respectable 8.8.
Keep in mind that F.I.R.I.S. scores are primarily subjective. While professional reviewers often use standardized scales to rate vehicles, there’s still some opinion involved in assigning ratings. And, of course, owners are likely biased (people tend to like their cars). So, F.I.R.I.S. scores are helpful, but only to a point. Purchase decisions must also reflect the other factors we covered (engine reliability, safety, fuel economy, upkeep, and market value).
Important Features Timeline
The Best Years of the Cadillac STS
Although new Cadillac STS models are things of the past, this premium sedan still has a following, especially for those looking for luxury on the cheap. These best-year examples are based on my review of FIXD Reliability Scores, government safety scores, fuel economy, market value, repair costs, and F.I.R.I.S. ratings. I’ve found that looking at common diagnostic trouble codes (DTCs) can also be helpful. This information offers a potential peek into the future and can help direct a mechanic’s attention during a pre-purchase inspection.
FIXD Reliability Score: 6/10
FIXD Internet Review Index Score (F.I.R.I.S.): 9.4/10
KBB Value: $4,398
Fuel Economy: 19 mpg
RepairPal Average Annual Repairs Total: $604
Safety Rating: 4.5/5
Winner, winner, chicken dinner—that’s how I’d describe the 2010 Cadillac STS. However, don’t expect this model year to be perfect. Its FIXD Reliability Score of 6 (out of 10) tells you this example is no stranger to check engine lights. But this engine reliability rating is far above any other STS model year (based on FIXD sensor data).
Like all STS editions, the 2010 is cheap to own. With a typical annual repair and maintenance bill of $604, this Cadillac won’t break the bank. And speaking of averages, the 2010 STS’s 9.4 F.I.R.I.S. score exceeds all other STS model years, meaning others hold this model year in high regard.
As mentioned, the 2010 STS stands out in the safety department with a near-flawless 4.5 (out of 5) in government crash tests. That inspires confidence, particularly if you carry passengers.
There’s another reason to appreciate the 2010 edition. It’s only one of two STS models not to have a recall. A recall isn’t always a reason to bypass buying a particular vehicle. However, the lack of a recall means the manufacturer built the car correctly in the first place, and there’s one less thing to worry about.
Meanwhile, 19 MPG isn’t close to what an economy car can deliver, but a thriftier vehicle won’t have tons of legroom and more than four cylinders under the hood.
The most significant error code to worry about with this Cadillac is P0305, a potentially severe misfire in cylinder five. With luck, the problem can be solved by replacing the spark plugs ($66-$250) or spark plug wires ($180-$240) or correcting a vacuum leak ($100-$200). Pricier fixes can include swapping out the ignition coils ($230-$640), fuel pressure regulator ($200-$400), fuel pump ($1,300-$1,700), or fuel injectors ($1,500-$1,900). Fortunately, FIXD sensor data doesn’t show this as a common occurrence. The same can be said for DTC P2601, a malfunctioning coolant pump.
Perhaps the greatest challenge with the 2010 STS is availability. Cadillac sold less than 4,500 examples in 2010, according to carsalesbase.com, a fraction of the over 33,000 that left showrooms in 2005. This translates into few for sale. A review of online for-sale listings (kbb.com, October 24, 2023) confirms the results; only ten 2010 STS models are for sale nationwide. There are two other best-year STS models to consider, which are covered below.
The KBB value cited reflects private-party sales; expect to pay more at a dealer where typical retail prices run $5,000-$8,000.
FIXD Reliability Score: 3/10
FIXD Internet Review Index Score (F.I.R.I.S.): 9.1/10
KBB Value: $4,579
Fuel Economy: 21 mpg
RepairPal Average Annual Repairs Total: $588
Safety Rating: 5.0/5
With a FIXD Reliability Score of 3, the 2011 STS won’t win any awards. Yet, it’s a reasonable alternative if the search for a 2010 edition is fruitless. Prices are similar to the previous year, and a 9.1 F.I.R.I.S. score is encouraging. But, like its predecessor, the 2011 STS can be hard to find (Cadillac sold about 3,500).
Plus, the 2011 model year stands taller than every other STS thanks to perfect NHTSA crash test scores and impressive (for a Cadillac) fuel economy of 21 MPG. Further, an average yearly upkeep of $588 makes it one of the more affordable STS model years to own.
What makes the 2011 STS a viable member of the best-years club is that even though it suffers from many check engine lights, the problems tend to be less severe. Yet, like the 2010 edition, when major problems arise, they’re usually connected to engine misfires (codes P0300 and P0306).
The 2011 STS has something else in common with the 2010 edition, no recalls.
FIXD Reliability Score: 3/10
FIXD Internet Review Index Score (F.I.R.I.S.): 8.8/10
KBB Value: $3,742
Fuel Economy: 19 mpg
RepairPal Average Annual Repairs Total: $646
Safety Rating: 4.5/5
Don’t consider the 2009 STS your best choice, but absent from finding a 2010 or 2011 edition, it’s the only way to go if you must have an STS in the driveway. It’s your last best option. Sure, that’s not a ringing endorsement. But what do you want for an almost modern Cadillac that you can pick up for around $5,000-$6,000?
Like its thumbs-up brethren (2010 and 2011), the 2009 provides reasonable fuel economy (19 MPG) and strong crash protection (4.5). Its F.I.R.I.S. score of 8.8 is at the low end, but there’s nothing wrong with a B+.
However, I mainly added this STS to the best years list because its many error codes don’t generally involve potentially catastrophic issues. For instance, owners may encounter a faulty catalytic converter (P0420 or P0430). This isn’t necessarily good news because replacing the catalytic converter can cost up to $2,400, but it’s much better than contending with a bad engine or transmission. Sometimes, the fix requires a new air-fuel or oxygen sensor ($200-$300) or an exhaust leak.
The 2009’s least-best status is also due to five recalls, mainly involving the car’s airbags and passenger crash protection system.
The Worst Years of the Cadillac STS
Determining if a particular model year deserves a “worst” label can be difficult. But coming across poor FIXD Reliability Scores makes the job easier. Generally, bottom-of-the-barrel rankings of 1 or 2 (out of 10) mean automatic assignment of a thumbs down. The trick is what to do if an STS scores somewhat higher. You’ll see how I handled the 2007 STS, which received a 3 for engine reliability.
I’ve skipped the discussion about market values and F.I.R.I.S. ratings to save time and space. This information isn’t consequential because you should avoid these STS model years.
FIXD Reliability Score: 1/10
FIXD Internet Review Index Score (F.I.R.I.S.): 9.0-9.1/10
KBB Value: $1,780-$2,107
Fuel Economy: 18 mpg
RepairPal Average Annual Repairs Total: $460
Safety Rating: N/A
I lumped the 2005 and 2006 model years together because both editions are equally terrible. Let’s put aside that 2005 is the debut year for the Cadillac STS (remember, I mentioned it’s best to avoid a first-year vehicle). A FIXD Reliability Score of 1 is a real indicator of unreliability.
Let’s put this ranking into a stark perspective. These two model years account for almost two-thirds of ALL the error codes (for all STS years) detected by FIXD sensors. Think about that for a moment.
What are the most frequent problems associated with the trouble codes? P0306, a misfire in cylinder six, represents one-fourth of all error codes recorded for the 2005 STS. If essential remedies (like new spark plugs or spark plug wires) don’t solve the issue, then more involved repairs (such as replacing the fuel pump) can cost up to $1,700, approaching the value of these vehicles. P0206, a bad fuel injector in cylinder six, is known to pop up, often requiring a replacement unit ($1,500-$1,900).
What’s worse is that most of the other error codes I’ve covered have also found a place in the 2005 and 2006 STS. This includes the troublesome (and expensive-to-fix) P0420 and P0430 DTCs, a faulty catalytic converter.
FIXD Reliability Score: 3/10
FIXD Internet Review Index Score (F.I.R.I.S.): 8.8/10
KBB Value: $2,489
Fuel Economy: 18 mpg
RepairPal Average Annual Repairs Total: $517
Safety Rating: 4.5/5.0
On the surface, the 2007 STS appears to be a candidate for a best years designation. Strong safety scores (4.5), low annual repair costs ($517), and acceptable fuel economy (18 MPG) are appealing.
A FIXD Reliability Score of 3 also looks promising, as other STS model years have gotten the seal of approval with identical rankings. But diving into this model year’s frequent trouble codes sends off the warning flares.
DTC P0008 and P0017 are among the most severe error codes that can occur in an STS or any vehicle and a known issue with the 2007 model year. These codes are a warning to pull over due to a malfunctioning timing chain. Failure to do so quickly can lead to catastrophic engine failure.
Without getting overly technical, the 3.6-liter V6 and 4.6-liter V8 used in the STS are interference-type engines with intersecting piston and valve paths. If the timing chain fails in an interference engine, these components can collide, leading to irreversible engine damage or a VERY expensive repair. FIXD sensor information shows the timing chain issue to occasionally occur in other STS model years, but not to the extent that it happens with the 2007 edition.
Seeing the high potential for this issue is the main reason I say run away as fast as you can from the 2007 STS. Its seven recalls don’t inspire confidence, either.
FIXD Reliability Score: 2/10
FIXD Internet Review Index Score (F.I.R.I.S.): 9.3/10
KBB Value: $2,715
Fuel Economy: 19 mpg
RepairPal Average Annual Repairs Total: $598
Safety Rating: 4.5/5.0
What’s almost as bad as a FIXD Reliability Score of 1? It’s a 2, the engine reliability ranking for the 2008 STS. This model year’s redeeming values (strong safety, decent fuel economy, and low yearly upkeep) can’t overcome a fundamentally flawed vehicle. FIXD sensor data shows this Cadillac has no trouble generating check engine lights for all sorts of problems.
Like the 2007 STS, this one has many reports of timing chain problems (P0008 and P0017), albeit not at as high a rate. Still, knowing you’re buying a car with an increased potential for an engine disaster would be unsettling for most people.
But there are more DTC troubles ahead. P0430, a malfunctioning catalytic converter, accounts for 25% of all error codes for the 2008 STS captured by the FIXD sensor. What’s even worse is that the cost of replacing the catalytic converter can approach the car’s value.
I’ll pour more salt on the wound by noting that the 2008 STS is subject to two recalls.
Cadillac doesn’t include a “high mileage” light with the STS (nor does any other automaker with its products). High mileage is a term that can have different meanings, depending on the vehicle.
Autotrader.com had 94 Cadillac STS models for sale (as of October 24, 2023). 11 had over 150,000 miles, and one crossed the 200,000-mile threshold. This unscientific analysis suggests a high mileage cap of 150,000 miles for the Cadillac STS. Search results show the STS can surpass this benchmark, but such achievement appears to be the exception, not the rule.
Proper maintenance and moderate use are vital to getting the most life out of a vehicle. Keeping up with all scheduled services allows a car to outlast one with irregular maintenance. Similarly, a vehicle mainly driven at highway speeds will typically outlast a comparable car used for demanding city driving.
The lifespan of a used car is best determined by a detailed pre-purchase inspection performed by a qualified technician.
Cadillac fans looking for an older sedan will want to check out the DeVille. Meanwhile, the SRX crossover and CTS are other options. Other Cadillacs in the lineup include the CT4 and CT5 sedans and the XT4, XT5, and XT6 crossovers. The ever-present Escalade is another consideration if a large SUV meets your needs.
Outside of Cadillac, but still in the General Motors family, are other sedans like the Chevrolet Impala, Buick LaCrosse, and Buick LeSabre. Non-GM offerings include the Lincoln Continental, BMW 5 Series, Mercedes-Benz E-Class, Acura RLX, and Audi A6.
A Note About Data and Information Sources
This article has many details about Cadillac STS reliability; here’s what we used for our assumptions and recommendations.
- FIXD Reliability Score & Data: Engine reliability information is captured via the FIXD App.
The FIXD Reliability Score is calculated using the number of DTCs per year, weighted by mileage using 12,000 per year. This is then turned into a scale of 1-10 for easy graphing.
This is an objective score.
- F.I.R.I.S & Data: This data is the result of averaging the score of the Cadillac STS from Edmunds, KBB, Cargurus, and Cars.com.
Those individual Scores come straight from reviewers and owners of the Cadillac STS.
This is a subjective score.
From here, we translate the answers into the F.I.R.I.S as all the answers are out of 5.
Keep in mind that owners may think their car is more or less reliable than it actually is.
One potential problem is that people often buy the same make or model they are used to when they go car shopping, just a newer year.
Ford, for instance, has a number of consumer loyalty awards for the Ford F-Series, Ford Mustang, and Ford Expedition.
Car owners may be so loyal to the make or model they currently own that they would have trouble accurately comparing their cars’ reliability to others.
It’s for this reason that we ask car owners a question that is relative to mileage rather than relative to other cars.
Still, be mindful of the accuracy of these F.I.R.I.S; people’s perceptions and unconscious blindspots can skew data.
We suggest looking at both the FIXD Reliability Score and the F.I.R.I.S for this reason.
- KBB Value: Average private-seller valuations as supplied by Kelley Blue Book (KBB), based on a Cadillac STS with typical mileage for that respective model year.
- Fuel Economy: Mileage-per-gallon estimates according to the EPA MPG on Fueleconomy.gov
- Annual Maintenance/Repair: Upkeep expenses as reported by RepairPal
- Safety Rating: Crash test data collected and reported by NHTSA. We average all ratings for each year to come up with a simplified, average safety score. This makes it easier to look at on a graph.
Dave Goldberg is an automotive journalist and lifelong car fanatic. He writes for numerous enthusiast and business outlets and is an ongoing contributor to HotCars.com, one of the most popular car culture websites. When he’s not writing or driving, Dave is either under a hood or asleep. His credentials include a BA in Journalism from The George Washington University.