I've had my '04 Z06 and GMC Envoy repaired by the GM dealership recently at no cost. Each was out of the stated factory warranty period however they still made the replacement as if it was warranted or in good faith.
Z06 window regulator went bad. Envoy threw a rod through the block and required an entire new engine. GMC covered both even though they were out of warranty! Yeah I was shocked.
I highly doubt BMW would do anything remotely close for my M3. It's like pulling teeth to get them to top off my engine oil and its still under factory maintenance and warranty period.