re: OT mechanics: Vehicle reliability - Mileage vs Age

Age effects rubber and plastic components. Rubber gets hard and starts to crack. PLastic gets brittle and breaks.
Doesn't matter what brand as a vehicle ages you need to start replacing plastic and rubber bits as the vehicle gets older. Good example is the plastic hose T's that get brittle and fail on older Toyotas. $11 part that takes 15 minutes to change. But can kill the whole motor if it goes and you don't notice. But those parts tend to be cheaper and easier to replace and usually a DIY sort of job.

Mileage equates to mechanical wear. Lubrication, heat, speed, and load all effect mechanical wear and can't really be judge by mileage itself.