Hey guys, first time here. I'm thinking of buying a 2018+ mercedes C300 sedan or coupe. I've been lurking on this forum for a while to see what issues these cars have, and it honestly scares me a little bit. I'll be looking for a C300 with less than 55k kms (34k miles). To my understanding, the 2018 C300s got the 9-speed auto and should not have the engine problems that the earlier C300s had.

My question is, how reliable is the car/engine really, and is it viable for me to own for at least 8 years off of warranty (I won't be buying extended warranty)? I'll drive the car about 9K kms a year, but it does snow 4 months of the year where I live, so it might wear the car a little harder.

My other choice is the 2018 Infiniti Q60 Red Sport 400. It's about the same price where I live compared to a 2018 Mercedes C300 coupe. I've owned my current Infiniti for 13 years and It's never given me any problems, but I wanted to experience a german coupe before I turn too old and need to buy SUVs.

Thanks!

C200 AMG line 2015 sedan German built. So far nock woods no issues at all except auxillary battery replaced and sunroof left rack replaced. The last was not the car's fault as a stone was found on the rack.

Mercedes: The Best or Nothing.

Had a 2017 C300 and the engine blew out at 45k miles. Car was very gently used and never pushed hard (it's a C300, not gonna get that much extra power if you push it). Luckily it was a lease so I was able to get it fixed under warranty and turn it back in. My goal here isn't to scare you away from this car, but the issues that people point out are very real. The blown engine would've cost me $13k out of pocket if I hadn't had warranty.

It doesn't matter whether you have the 9 speed automatic or the older 7 speed automatic... the engine is the same from 2015-2018 model years and is susceptible to piston cracks and the motor blowing. The 2019+ model years have a different engine so they may not have the same issues.

How come my engine did not blow up at 45,000 miles? My odometer is now at 90,000 kms. How come my pistons did not crack? We should not generalize things. I am a member of a local W205 club we always meet talk no one mentioned engines blowing up or pistons cracking. Maybe because ours are German built? If these issues are specific to US built C300s then my dear OP I dont recommend buying a C300. How about you a C43 coupe before you get too old and buy an Infinity 😃

Like I mentioned in my post, my intention isn't to scare OP away from the car. But it's also incorrect to ignore the very real issues that some owners are experiencing with this car. Nothing wrong with being aware of these risks. For every 1 bad C300, I'm sure there are thousands of good C300s with no issues. The only question is how much risk you're willing to take and that's completely at OP's discretion.

Trust me the OP will run to the Infinity after reading your post 🤠 there are the goods and the bads in every car. For me my W205 is the first MB car I owned. It is an amazing car combining luxury with sport. I am very happy with it. I take care of it always serviced at the dealership. Its a 2015 model still looks good.

What I am getting from RUNSGR8's post is that Mercedes has inconsistent product quality, and inconsistent dealer care/experience. Some owners experience no product defects and wonderful dealer experiences, while other owners experience cracked pistons, scuffed cylinder bores and oil wicking into wiring harnesses. The product defects are inherent in the design and manufacture, statistics being what they are, means some people are lucky, others aren't. Ditto for dealer support and care.

Inconsistency is the very definition of poor quality. Mercedes is delivering a poor quality product and dealer experience.

My 2015 had an engine rebuild because of wrist pins, and that repair would have been over $11,000 if I did not have a warranty. It didn't have any problems drivability-wise, but you could hear it pretty loudly. Not good.

In January of this year I had a massive coolant leak from a cracked hose that left me stranded in my garage (thankfully) and covered by aftermarket warranty (almost 60k miles)

Then in March I had another massive leak but this time it was oil. Stranded at work. Oil lines replaced by aftermarket warranty.

Current issue is that my auto start/stop has stopped working and the button is no longer green. Not really an issue since I don't care and turn it off anyway. Don't care enough to get it looked at.

I've also heard of piston cracking (mainly cyl no. 1 it seems) due to cheaper gas used in longer periods. At least that's what my dealer tech said.

This is just my experience and my 2015 was one of the first built, but pretty inconsistent build quality overall. Others have been extremely reliable and then there's others who are worse off than me.

Thanks a lot for all the feedback guys, I super appreciate it. It honestly doesn't sound like these cars are built to last me 8 years. I'd be absolutely pissed if I have to spend $13K to re-build an engine, thats literally the cost of a used economy car... I think if a good deal pops up under 28K for a 2018+ car, I may get it as there'll be a little buffer for things to go wrong. But other than that, I might just stay away for now.

I would get the infiniti and get a catch can installed on it and call it a day. Owning 2 cars with the M274/9g-tronic (GLC and E) - these cars are a bit worrisome. Everything is expensive to repair. I considered trading in my 2017 E but the value to do so isn't there unfortunately.