4-5 year old MB's are pretty reasonably priced (I tend to buy a little farther out on the price curve than that).
Mercedes also had a horrible rust problem with their mid-late 90s cars. They switched to an environmentally friendly paint process that was terrible for paint adhesion and rust prevention. I have a perfectly good '98 E300D that's going to go the junkyard because of rust issues. Explain to me how that's saving the environment again?
By rusting away, the car will turn into iron oxide, which is "natural" and thus helps the environment. They should have made the paint an energy source for microorganisms, then they could claim to have a biodegradable car.
I've been in a climate known for being hard on vehicles (Minnesota) for ten years and the only rust buckets I ever see on the roads are older American vehicles (Dodge SUV's and minivans in particular). I've owned Nissan and Honda vehicles in that time and never had issues with rust.
My relatives have no problems with Toyota cars since ~2009, unlike previous Big 3 vehicles with a continual trickle of issues, even in brand-new vehicles. Plus they're just nicer on the inside and hold up longer.
Not everyone can afford a Mercedes.