Looking into buying a used P85 and was wondering something. The car will have 8 year unlimited miles warranty on motor (drive unit) and battery right? It has a 4 year 50k mile bumper to bumper. My question is before your bumper to bumper warranty runs out (4 year 50k miles) you can pay $4k, to add additional 4 more year and 50k bumper to bumper coverage to the car? What if you never take it into the service center for an annual service.