These luxurious Mercedes-Benz and BMW cars were heavily impacted by depreciation, but they're far from being used bargains.

For decades, both Mercedes-Benz and BMW have remained at the upper echelon of luxury vehicles thanks to their exquisite engineering and supreme finesse. But just like every other automobile brand, Mercedes and BMW still missed the mark for some of their models in terms of reliability. Getting an unreliable car, especially if it's used, will mean you have to bear plenty of repair costs in the long run.

Related: 5 Coolest Mercedes-Benz Cars You Can Buy For $15,000 (And 5 BMWs) Besides being unreliable, some Mercedes and BMW models are a complete write-off when it comes to the quality of their interior/exterior materials, performance, and safety. Making the mistake of getting any of these models will be tantamount to buying trouble for yourself. Having taken the time to pore over reliable sources such as Consumer Reports, RepairPal, J.D. Power, CarComplaints, and Mercedes Medic, here are the five used Mercedes-Benz cars to avoid (and 5 BMWs).

When it comes to the Mercedes-Benz E320, each model year has its own issues to grapple with, but the 2003 model year stands out as the most problematic. According to CarComplaints.com, the most common problem with the 2003 E320 is brake failure that costs roughly $2,500 to fix.

Since the 2003 Mercedes-Benz E320 is no longer in production, you have to know that getting a used one will not only empty your pockets but will put your life in danger, as you might find it difficult to stop, even when you are going at a pretty low speed.

The BMW 3 Series can capture your attention with its long list of luxurious features in its sedan, sports wagon, or hatchback form. However, we will let you know for free that the 2011-2014 model years are plagued with a myriad of issues.

When you think of a reliable BMW, the 2011 3 Series should not cross your mind, as it has a total of 11 recalls due to issues involving the airbags, engine, and a host of other parts. BMW 3 Series also complained about the battery, alternator, coil, and body integrity.

Related: These Are The 8 Best Versions Of The BMW 3-Series Ever

The 2006 Mercedes-Benz E350 was an improved version of the E320, as it featured a stronger engine, which in hindsight was more problematic, and new seven-speed transmission.

But Mercedes failed to tie up loose ends with the 2006 E350, as it gathered over 110 complaints from users. In fact, CarComplaints.com labeled it as the worst E350 model year because of its engine problems such as balance shaft failure, malfunctioning car jerks, and oil pump failure.

First off, we give the 2011 BMW 5 Series credit for its agility and seamless handling. This luxury sedan offers a very comfortable ride, but that's just about all it has going for it. Consumer Reports points out that there are over 9 recalls on the 2011 BMW 5 Series.

Owners cited the rear lighting, improper battery size, 12V power plug, emission control devices, and fuel injection system as some of the trouble spots of the 2011 BMW 5 Series.

Related: 10 Modern Executive Cars To Consider Instead Of BMW 5 Series

When you break the bank to get a vehicle, you'd expect it to serve its purpose and stand the test of time. But that's not the case with the 2015 Mercedes-Benz C300. This luxury small car is supposed to be an elegant, sporty competitor with the Audi A4, but it doesn't live up to expectations.

There have been over 257 complaints about the C300, with its broken piston being the most expensive to fix. It's also on record that the 2015 C300 has been recalled 12 times for mechanical and electrical issues.

Adding the BMW X5 to this list might come as a huge shock to some, as it features a turbocharged six-cylinder engine that combines with an eight-speed automatic transmission to deliver agile cruising. But we can't turn a blind eye to the dozens of problems that bedeviled the 2012-2014 BMW X5.

Going by the data from Consumer Reports, the 2012 BMW X5 alone has over 14 recalls. J.D. Power seems to agree with Consumer Reports on the reliability and quality of the BMW X5, thus giving it a less than average rating.

To be blunt, Mercedes did not put in the extra effort to make the 2019 GLC better than its predecessors. The only significant improvement of this model year is the inclusion of the Off-Road Engineering system that can be installed in the four wheel-drive versions. The steering wheel remains lackluster, and the technology interface is still not user-friendly.

The 2019 GLC has 11 recalls due to fuel leaks, eCall system failure, power supply cable damage, airbag failure, and lots more. With all of these issues, the 2019 GLC finds it difficult to go head-to-head with the Audi Q5, which was the original intention of Mercedes.

Related: Here's How The Mercedes-Benz GLC Stacks Up Against The Luxury SUV Competition

Just like all other BMW models on this "never buy" list, the 2014 BMW does not have much going for it, save its superb handling. Consumer Reports records that the SUV is below average when it comes to reliability. The 2014 X1 has 5 recalls and over 72 complaints filed with the National Highway Traffic Safety Administration (NHTSA).

The most prevalent issue with the 2014 BMW X1 is the diesel engine. According to What Car, many complaints about the X1 2.0-liter engine are centered around snapping and stretching of the timing chains, and repair may cost almost a thousand bucks, according to RepairPal.

The 2020 GLE is a luxurious SUV that Mercedes markets as a “more intelligent SUV”, but in reality, it's a complete disaster. Let's not even begin with the lackluster handling for a car that's supposed to compete with heavyweights like the 2020 Lexus RX. Skimming through Consumer Reports, you will be quickly taken aback by the number of times this luxury SUV has been recalled. A freaking 27 times!

The recurring issue owners of the 2020 GLE have to deal with is the speed control system malfunctioning. A reviewer on Edmunds pointed out that he has adjusted the sensitivity of the Early Collision Warning System up to 6 times in a space of 7 months due to this malfunction. Complaints have also been filed regarding the rear windshield, airbags, and fuel tank.

At first glance, the 2020 BMW X3 doesn't come off as shoddy. In fact, you might be swayed to believe it offers the luxury, comfort, and utility that you desire in a crossover, but it fails to live up to expectations in terms of reliability. According to the U.S. News, the 2020 BMW X3 has 12 NHTSA recalls for issues involving the engine, camera sensing system, battery, steering, airbags, and lots more.

Apart from the tons of issues plaguing the BMW X3, you still have to cough up roughly $1,034 annually just for maintenance. While the amount is not the highest out there, it's still pretty much expensive for many to afford.

These modded Mercedes are pure perfection, but we'd rather own these modified BMWs any day.

Peter Akpejeluh is a content writer with years of experience in the automotive industry. His love for cars makes crafting colorful stories around them quite effortless. When Peter is not developing automotive content, you can find him taking one of his favorite cars for a spin.