I just bought a 2016 C=Mac Energi with 63k miles. We are enjoying the car but when the hybrid battery is depleted and the engine starts the car has a loud, deep whine that is present at high speed or in town. When in town the whine is extremely irritating and often interferes with conversations. I took the car to our local Ford dealer with a response of nothing is wrong with the car and the dealer service representative stated they have another C=Max in the shop that does the same thing so it must be normal.
