I think the issues raised by the rusty seat frames are more complicated than the obvious ones -- like whether the rust is surface rust (which may need period cleaning to prevent deterioration), or whether the affected areas are out-of-sight (and therefore out-of-mind).
Remember these are brand new cars that just rolled off the production line. The type of rust reported should only be evident on internal (not exposed to moisture) unpainted metal surfaces after many years, not straight off the production line. There should be ZERO rust in a brand new car whether it's a BMW, Hyundai or Great Wall.
The questions that come to mind:
- Are the materials used sub-standard or defective in some way? If so, what other sub-standard/defective materials are used in the car?
- Were the materials inadvertently exposed to moisture/corrosive agents during manufacture? If so, is the problem limited to the seats, or does it affect other components?
- If such an obvious problem slipped through BMW quality control, what other potential problems are lurking in the car?
- If BMW insist on repairing/cleaning the affected seats instead of replacing them, will they guarantee the repairs in writing over a reasonable period (say, 10 years)?