We makes all sorts of assumptions about the cover the manufacturer's warranty gives us, and we usually only find out what it doesn't cover when we strike a problem and find we're not covered at all.
In essence, the warranty covers us against design and manufacturing faults that might crop up for a period or time or distance, whichever comes first. What it doesn't cover are the bits and pieces, known as consumables that regularly wear out or are replaced as part of regular servicing.
Parts replaced during servicing are oil, oil filters, air filters, fuel filters, cam timing belts, spark plugs, spark plug leads and the like. Most owners are aware of the need to replace these parts and accept their replacement without complaint.
Other parts that aren't covered, and not regularly replaced as part of the service routine, are brake linings, brake rotors, clutches and tyres etc. that inevitably wear out requiring replacement at the owner's expense.
Complaints usually relate to these parts when they wear out faster than we expect and cost more to replace. Brake linings and rotors wear out much faster on today's cars than there ever did on cars in the past, much to the consternation of their owners.
It has to be kept in mind that the braking performance of our cars is much higher than it ever was, the speeds we travel at and therefore have to brake from are much higher than they have ever been, the traffic we have to endure every day is much more congested then it has ever been, we have more traffic lights, stop signs, give-ways and speed zones than we've ever had, and we never used to have speed humps. All that contributes to brake wear, so it's no wonder our brakes wear out faster than they have ever done before.
Clutches are also a particular complaint and wear out much faster than they have ever done in the past, but manufacturers are designing their cars closer to the limits of weight and performance than they have ever done, so clutches have less tolerance in them than they once did.
Tyres also wear out faster. Cars today are heavier, suspensions are set more aggressively, engines have more power so the cars are faster, they brake more powerfully and all of that finds its way to the tyres that have to work much harder than the tyres of old.