[Flying Ace]

Something doesn't sound right here. Either your perception of what the dealer told you was not correct or the dealer was not correct. Did you actually provide a VIN to them so they can run the quotes? That's the first step. Did you discuss exact original/CPO/extended warranty start and stop dates? That's the 2nd step to clarify WTF is actually going on here.

If your used M5 is currently under existing factory warranty and had a record of correctly performed break-in service, then ANY BMW dealership should be able to sell you a BMW extended warranty.

Sure, a dealer can peddle both 3rd party and BMW branded warranties, but if I were BMWNA, I'll be pissed to find out my franchise was promoting 3rd parties over the company's product.

That said, if your car is not under original factory warranty, AND less than 1 year has passed since the expiration, you can STILL buy a BMW branded extended warranty albeit at higher prices and slightly less menu items to choose from. So inquire about this as well.

There could be a miscommunication such that the dealers were indeed selling CPO cars and construed your inquiry that you wanted to buy MORE warranty AFTER the CPO expiry. In that case, I believe only 3rd party warranties are available as BMW branded warranties cannot be sold more than 1 year after original factory warranty expiry date.