On the fence
But as for a direct answer to your question, I'd buy a CPO from a MB dealer with maintenance package o make sure most of the items are covered. I'd never buy a German/luxury car from a private dealer unless I 100% trust them.
Total cost of ownership has different flavors according to brand. These are broad sweeping statements but are not far off:
- American cars: cheap price, low to moderate maintenance cost, disintegrate quickly
- German cars: moderate to high price, moderate to high maintenance cost, long life
- Japanese specifically Toyota and Honda (including Lexus and Acura): moderate to high price, low to moderate maintenance cost, long life
Lexus in my opinion is now in the sweet spot of total cost of ownership in the luxury segment.
It is a personal choice between brand image, specific features and performance levels, and total cost of ownership. I choose Mercedes. My wife chooses Lexus. Others choose as they choose. There is no right or best answer.









