When it comes to discussing reliability and maintenance costs in general, people often like to compare popular brands like Toyota and Porsche and pit them against each other. One of the most popular topics that pops up time and time again is BMW VS Mercedes reliability.
Both of them are arguably the two most popular German luxury car manufacturers of all time (in addition to Audi), so it’s no that wonder people like to know which one comes out on top. Answering that question though isn’t as easy as it appears at first glance.
There are many ways to measure reliability and durability. What’s more, each German manufacturer has several different vehicle offerings in its lineup, all belonging to a different class and a different bracket. Comparing brand reliability as a whole then is pretty much pointless unless you directly compare apples to apples or car to car in this case.
In this article, I’ll be highlighting each manufacturer’s respective model and their differences, as well as their reliability. To accurately rate them and give you some indication into how reliable they are, I’ll be using multiple sources from sites like J.D. Power and Reliability Index, as well as forums and various other magazines and YouTube videos.
Do not take these videos for granted and only use them as a rough guide, as not all the issues I’m about to point out can or will happen to each and every car of that model. What I’ll be simply pointing out are weak points which can fail or usually end up failing first, but that doesn’t necessarily indicate that that’s always the case.
If you’re serious about buying one of these cars, use this article as a guide but also consult with a professional and get a third-party inspection before committing to a purchase. Even the most unreliable car can be decently reliable when maintained properly, and vice-versa.
For the purposes of this article, note that I will be using reliability indexes taken from ReliabilityIndex.com which might be outdated and/or missing information for certain cars. They in turn use data from Warranty Index, a company which shells out millions of pounds each year for car repairs. Note that lower values are better.
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1-Series vs A-Class
The 1-Series is BMW’s smallest model and is also one of their most popular as of recent years. First and second-gen cars were rear-wheel-drive ordeals, with BMW deciding to make the switch to a new FWD platform for its 1-Series just a year ago.
The move was met with criticism from the car enthusiast community, as the 1-Series was the only rear-wheel-drive car in its class. Nonetheless, the new 1-Series is a massive success as most owners don’t really care that it’s FWD.
The original 1-Series is a car plagued with quite a few issues, the majority of which are electrical and engine-related. Most 1-Series use a four-cylinder petrol or diesel engine, but all of them have one massive flaw: the timing chain can fail and take the engine with it under certain circumstances.
Replacing the chain itself isn’t difficult, but getting to it is, as it sits behind the engine near the bulkhead. Effectively, what I’m saying is that the entire engine has to be dropped to perform this service.
Average repair costs for the 1-Series are $700. The rest of the car is bulletproof though, especially the gearbox and the steering. If you can deal with potential timing chain issues in the future, it’s still the best driving car in its class.
It has a reliability index of 136.
The Mercedes A-Class is Mercedes’ smallest offering and it shares its platform with its much bigger siblings, the CLA and GLA, which we’ll get to in a minute. It’s available only as a front-wheel-drive car, and some iterations of it use a Renault engine (such as the A160d for instance).
Average repair costs for the A-Class stand at $620, which is $80 cheaper than the 1-Series, but then again it’s also a much newer car as it was introduced later than the BMW. Most of the issues are overwhelmingly related to electrical components such as sensors. A whopping 38% of all common issues have to do with some electrical part.
It has a reliability index of 132. (Note that lower is better)
If I had to call it, I’d say this BMW VS Mercedes reliability battle goes to the Mercedes.
3-Series vs C-Class
Here’s where we get to both manufacturer’s bread and butter. The 3-Series has been BMW’s best-selling car for ages, and it’s not difficult to see why. Motoring journalists often praise it for its incredible handling and stout engines, as well as its responsive and dynamic steering.
Despite that though, earlier iterations of the 3-Series perform extremely poorly when it comes to reliability. Average costs of repair are $720 according to Reliability Index, which is only slightly worse than the 1-Series, but it has a much worse index overall because of some major engine issues associated with the larger petrols and diesels such as the 335i.
The 3-Series shares most of its engines with the 1-Series, so it’s small wonder that it’s also plagued by the same issues and faults. The most expensive of the bunch is the 335i, especially the earlier E90 generation, as there’s a lot that can go wrong with it, including but not limited to turbochargers, wastegates, fuel pumps, intake pipes, etc.
If you can live with a slightly more unreliable car and can commit to a more rigorous maintenance schedule, the 3-Series is still an excellent buy, and arguably your only choice if you want the most driver-focused vehicle from this segment.
The 3-Series has a reliability index of 216.
In contrast to the 3-Series, the C-Class is ranked as one of the most reliable cars in its class. Average repair costs are way lower compared to the Beemers, standing at just $250. Most have to do with suspension components and axles.
I feel obliged to point out one thing here though: most C-Class vehicles on the road, especially earlier W204 generation cars, are diesel, particularly in Europe, whereas plenty of people who opt for BMWs choose petrols.
Mercedes is notorious for its diesel engines, hence why I think this comparison between the 3-Series and the C-Class might be a little skewed. Another note: the newer W205 generation is much worse compared to its predecessor when it comes to reliability, putting it more on par with the 3-Series.
The C-Class has a reliability index of 23. (Note that lower is better)
Despite being a great car to drive, the C-Class has to get the nod in this BMW VS Mercedes reliability duel.
5-Series vs E-Class
The 5-Series is one of the best driving in its respective segment, hands down. For such a large luxury saloon, the way it can smoothly drive down any stretch of road is nothing short of a revelation. Even base non-M cars have sporty enough suspension to make them feel fun.
With the exception of some E60 generation diesels, the 5-Series has proven itself to be an extremely reliable motor vehicle. The latest G30 5-Series is quickly proving to be the best one yet, but the F10 which preceded it is not far behind.
When you read that average repair costs for the 5-Series stand at an eye-watering $700 you might think I’m talking nonsense, but hear me out. We’re now stepping into the realm of large, luxury saloons, so naturally parts are going to cost more.
The largest issues with the 5-Series are, once again, engine and electrical components, but not nearly as much as on some other BMWs.
Trumping both smaller siblings, the 5-Series has a reliability index of 158.
The E-Class has always been much softer and more relaxing than the 5-Series, and anyone who’s ever been in one will tell you this. The ride is smoother, the chassis rolls more, and it just feels like a ‘lazier’ car to drive overall.
Fortunately, the E-Class is one of the easiest luxury saloons to own, as the average repair cost is just $510. Yes, that’s still quite a lot, but it’s $190 cheaper than the 5-Series estimate.
In general, the engines are pretty stout and most issues arise from electrical components or the cooling and heating system. As all Mercs, it tends to eat up suspension components too.
The E-Class has a reliability index of 80. (Note that lower is better)
7-Series vs S-Class
We’re now inching towards cars that offer more features in the back row than they do in the front. The 7-Series is the largest car BMW currently makes (that’s not an SUV), but it’s also one of their least popular ones, at least in Europe.
I hate bashing cars, especially ones that I love the look of, but the 7-Series is absolutely woeful when it comes to reliability. Plenty of YouTubers have taken on a 7-Series as a project car and have gone on to regret the decision, and for good reason. Most old 7-Series are serious money pits, and basically, anything that can go wrong will at one point or another.
I hate to sound like a pessimist, but I’ve seen it all too often. The latest 7-Series seems to be a step in the right direction if you can live with the grille, but I’d avoid previous iterations of it if I were you. Average repair costs are an unbelievable $830.
It has a dismal reliability index of 319.
The S-Class is the car which practically pioneered the entire luxury limo segment back in the early 1970s with the W116. Chances are most of the features you have on your car right now first made their debut on an S-Class a decade ago, as they slowly trickled down and found their way on regular cars years later.
It’s an S-Class, so of course, repairs aren’t going to be cheap, but they’re still slightly less than the equivalent BMW, standing at $635. That being said, the S-Class is loaded with features and gadgets, all of which can go wrong at any time. It’s also a heavy car, so it likes to use a lot of brakes and suspension parts.
It has a worse reliability index than the 7-Series, but I feel like they’re equal in that regard. Once you surpass a certain threshold it really doesn’t matter anymore, as they’re both going to cost you a ridiculous amount of money to keep on the road if bought second-hand.
The S-Class has a laugh-inducing reliability index of 345. (Note that lower is better)
When it comes to large limos there’s no comparison. The S-Class easily wins the BMW VS Mercedes reliability argument.
X1/X3 vs GLC/GLB
GLC/GLB: Not recorded
The BMW X1 is listed in Reliability Index’s website as one of the most reliable BMW’s ever made. Sharing a platform and most of its components with the X3, the X1 was actually introduced in 2009 as BMW’s baby SUV.
By that time, BMW had sorted out most of the kinks on the first-gen X5 and X3, so they were ready to bring something a little more reliable to market. The site lists a ridiculous $1280 average repair cost, which is wrong, especially since it has one of the best reliability indexes of any BMW.
Regardless of that glitch in their database, the X1 has a reliability index of 92.
The Mercedes GLC is the company’s mid-size crossover SUV, and it was first introduced in 2015, some 12 years after the first X3 made its debut in 2003. The GLC quickly became Mercedes’ most popular SUV, surpassing the GLK which preceded it and even the ML.
Even though the site has no entries for the GLC/GLB, I can tell you from personal experience that it’s a relatively reliable car, especially with the smaller 2.0-litre diesel engines. As most new Mercedes cars, the one issue people often complain about is poor build quality in the cabin and squeaky trim pieces.
The interior looks nice but it isn’t as well-built as Mercedes cabins in the early-to-late 2000s. Since it has no reliability index, I’ll assume it’s similar to the X1 based on things I’ve been able to read on forums and watch on YouTube videos.
Because of its better build quality and great engine lineup, I have to give this BMW VS Mercedes reliability battle to the BMW.
X5 vs GLE
The BMW X5 is the company’s most popular SUV to date, and is arguably their most profitable model. It saved the company from the brink of extinction back in 1999, and it practically invented the SUV segment on its own. It was the first truly sporty off-roader which could handle pavement as well as light dirt trails.
Average repair costs according to Reliability Index stand at $815, but I think the sum is lower since you can find third-party AEM parts for a much cheaper nowadays. Most issues with the X5 stem from axles and suspension components, which is a given since it’s a heavy 4×4 with plenty of moving parts and bushings.
It has a reliability index of 254.
The Mercedes GLE is a relatively new model but it’s a model which ultimately replaces the old ML. The old ML was a car which didn’t have a shortage of electrical problems and the chassis was susceptible to rust in rainy and cold environments. It had a reliability index of 289 according to Reliability Index’s website.
Although they haven’t ranked the latest GLE as of yet, I expect it’ll be a similar ordeal to the new E-Class as that’s what it shares most of its cabin and features with. In all honesty, Mercedes’ latest lineup is too new to be able to tell whether the cars will withstand the test of time.
So far, new Mercs have been plagued with interior build quality issues, but they’ve gotten round to resolving a lot of those complaints are in general the fit and finish is improving constantly.
I have to call this BMW VS Mercedes reliability battle a draw.
X7 vs GLS
X7: Not recorded
I’m fortunate enough to have a friend who just bought a new X7 so I can tell you about the issues he’s had so far. The car’s been pretty much faultless really, which isn’t surprising considering it isn’t even a year old yet, but he’s had to go to the dealership twice to fix a minor electrical niggle (the sensor for the second row was out and it was throwing an error on the dash constantly).
The engines are really strong and proven, especially the smallest 30d as it’s the least complicated. I’d be wary of the quad-turbo M50d especially once the warranty runs out and you’re on your own. You’d basically be asking for trouble at that point.
The Mercedes GLS, having been released just last year, is the BMW X7’s main competitor. The latest generation is all-new, but the one which preceded it was actually based on the old GL, it just used a different moniker and featured slight exterior alterations.
Like all large and heavy cars, including the X7, the GLS will suffer axle and suspension components failure over time. According to Reliability Index, an average repair will set you back $770.
It has a reliability index of 539 according to the website, which I think is significantly off where the car should be.
In this BMW VS Mercedes reliability battle I’d say it’s once again a draw, as both cars are extremely new and no significant reliability conclusion can be drawn from them.
M3 vs C63 AMG
C63 AMG: Not recorded
The BMW M3 is a car which needs no introduction at this point. Whether you want a naturally-aspirated V8 or a turbocharged straight-six monster, there’s an M3 generation to suit everyone’s tastes and needs.
The old E92 was notoriously famous for its rod bearing failure, a common issue which usually occurred within the first 100,000 miles. Plenty of people replace the stock rods with AEM ones for peace of mind, but it’s an operation which will cost you several grand.
The newer F80 M3 has potential issues with its crank hub bearing, namely under the right conditions and with a failing part, the crank hub can spin causing all kind of engine mayhem. It was nowhere near as troublesome as its predecessor’s rod bearing issue though, and in general, it was blown way out of proportion online.
The site rates the M3 as having a reliability index of 405, which doesn’t sound bad compared to some of the cars on this list, but I think it’s even better still. If you buy an M3 expecting Toyota Yaris reliability or service schedules, you’re in for one hell of an awakening. Have realistic expectations though, and you might be surprised to find out it’s actually not an unreliable car.
The C63 AMG, of any generation, is a car which likes to guzzle fuel faster than you can fill up. The old W204’s 6.2-litre V8 is a proven engine which has seen plenty of usage in most of Mercedes’ racing cars.
The real issue with the big V8 stems from the head bolts which have a tendency to break, allowing coolant to enter the engine and seize the motor. Early warning signs include a low coolant light on the dash, frequent misfires, and the all-too-familiar check engine lamp. People recommend replacing the head bolts as a preventative measure as you can never be too careful.
Other than that, the car is pretty much bulletproof all things considered. The automatic transmission hardly requires any maintenance and the cabin feels well put together, but you will have to shell out a ton of money for tyres and brakes.
The newer twin-turbo car is, dare I say it, even more reliable than the old one, and it has an enormous amount of tuning potential. Again, no reliability index is given, but I have a feeling it’d be on par if not slightly better than the M3.
In this BMW VS Mercedes reliability discussion I have to give the slightest of advantages to the C63 as it is far more simple and therefore less can go wrong with it.
Comparing reliability is never as simple as adding two and two together. Models and engine choices greatly vary how dependable and reliable a car is. The disparity in reliability you can find between different models within the same manufacturer is shocking.
If you’re looking to buy a BMW or a Mercedes, get a pre-purchase inspection performed by a third-party and don’t risk ending up with a lemon.