Are oxygen sensors on BMW covered under emissions warranty?

The BMW Service and Warranty Information book for 2009 has a table for all emissions parts warranted past the 3 year 50,000 "all inclusive" warranty for states like California which mandates emissions coverage. The coverage varies greatly across models for the extended coverage (7 year 70,000 miles or 8 yr, 100,00 miles). For instance, the 328xi front and rear( pre and post catalytic converter) O2 sensors are both covered. For the 550i and 650i neither are covered. For the 528i, only the front O2 sensor is covered. The California Air Resources Board told me the law's intent is to require the manufacturers to warranty parts that have a high replacement cost for a longer period. Some dealerships would have you believe nothing is covered past 3 years or 50,000 miles.