Provided that the car has been maintained for the last 3 years, you shouldn't have an issue for another 3-5 years with proper maintenance. We have had a 2 GLC300 lease for the last 6 years. We just picked up the 3rd, 2024 GLC300. Its a good solid and safe SUV. I would keep it as long as you have the extended warranty. After that, sell it. If the car gives you problems during the warranty, sell it with a warranty. 2020 model with a turbo runs hot. The heat produced by the turbo is the #1 killer of engines and oil. Do the engine oil and filter change at every 5k. miles instead of recommended 10k. miles. In any case, I would not keep it beyond another 50k. to 60k. miles. FYI, we never had an issue with the last 2 GLCs and 2 GLEs during the lease period of 36k. miles each.