Manufacturers generally certified recent car models that have relatively low mileage with no history of serious damage.

In most cases, this is defined as a specific number of repair attempts (eg four attempts to repair the same problem) or a certain amount of time while the vehicle is being repaired (for example, four weeks).

The reason for vehicle warranty is to provide protection in the event of your car needing major repairs.

And it is business sense for them to try to sell you only that brand and no other.