It depends on the manufacturer, and mileage. If it is a used car most Manfacture Warranties (MW) still cover the car up to 100K. Most MW cover bumper to bumper up to 100K miles.
That includes just about everything on the car, except the bumers (I don't know why! ) There are also other MW that include engine or transmission work up to 50K. It really differs per Manufacturer.
I think the purpose is geared towards marketing, and boasting reliability. "Our cars run so good we'll guarantee it with a Warranty. " "All our cars come with Warranties, so no matter the circumstance, you'll be covered."
I know dealerships also have extended warranties that again play on marketing. "You will have no worries with your car because of our extended warranty program"...and you have to pay $3500 for it.mahalo.com»