Modern engines are built very well, but they all need regular maintenance. One of the engine rebuilds we have on the go is a Mercedes diesel GL350 that was brought in with a complaint of blind spot monitor not working.
Before we looked at the vehicle we could hear it coming. The blind spot monitor was the least of the issues and it was apparent from the noise that the timing chains were stretched and slapping inside the engine. There was also major oil leaks, suspension issues, leaking oil cooler seals and a host of other issues. It was obvious that the Mercedes had not received much, if any, of the maintenance it needed over the years (it was a new customer). The engine was torn down and the analysis was accurate. The main bearings were chewed up, the timing chains were stretched beyond limits - it was time for an engine rebuild. When I asked Renato how a car could get this bad he said it was simple - limited oil changes and lack of any basic maintenance. Although the car had a bit over 200,000 km (it was a 2011) there is no reason why it should not have gone further with a bit more care and attention.
We don't just say that lightly either, we prove it daily. We have a fleet of Mercedes customer courtesy vehicles from a Large S class to C class and they range from 110,000 km's on our C240 to 645,000 km's on our E class. All of them get regular service here and we expect they will continue to last. Its part of our commitment to what we do and the longevity of the cars is a testament to that.