If I am not wrong then adulterated fuel usage fells under the category of ignorance by customer and warranty isn't entertained in this case. If my understanding is correct then they are hiding some other defect under the name of adulterated fuel.
Yes they are hiding some issue, usually diesels have this issue and its not very hard to find vehicles affected with such issues, adultrated fuel based issues can be best identified with
lack of Power,
blue,black,white smoke from exhaust,
Unconditional vibration from engine after pumping
And mostly diesel is what gets adultrated most while petrol adultration is extremely rare,
On another note Ford,VW,Renault all 3 are said to have fuel injectors,getting replaced for such reasons like adulteration a lot of times, there have been lot of such cases reported and most of them un reported since they get the job done under warranty.
I for one believe its mostly manufacturing defect or some other issue like low injector pressure that eventually causes damage to injector or rated electronics that causes the issues,
Ford s solution is simple, the Ford guys check OBD,EGR,turbos,and priming test with some other fuel, if the issue persists they will blindly replace injectors or the block itself, because down hunting the issue takes time and lot of expertise, they just order a new Crate engine and associated parts from Ford inventory and replace whatever they feel could be causing issue,
This happens with Maruti, as well but again nobody reports it.
So we cannot go into a hard core conclusion that its a Ford reliability issue, its there for lot of brands but mostly European brand customers have this issue reported most number of tines,