True, but you presumably must have regarded it as something to potentially be taken seriously (qualitatively, if not quantitatively) when your prefaced your introduction of it with "...another issue is the drop-off in performance as they age ...".IT IS NOT 'MY' FIGURE!
As you said of my car, if all 'they' were doing was finding a contorted way of expressing the fact that maintenance costs would increase with age, then they were merely making a statement of the obvious
Kind Regards, John