Try not to panic.
BMW has just issued a recall for 42 2015 to 2016 BMW M3s, M4 Coupes and M4 Convertibles due to the vehicles' driveshaft. The National Highway Traffic Safety Administration discovered that a collection of M3s and M4s have a slip-joint in the driveshaft that has not been filled with grease. While that may not seem like a huge issue, there's a chance the slip-joint could fail, resulting in a loss of power to the rear wheels over time. The loss of power could increase the risk of an accident.
The models being recalled in the US are M3s that were produced this year between May 30 and September 2, M4 Coupes produced between July 3 and September 11, and M4 Convertibles made from May 29 to August 4. In all, 42 vehicles are being recalled. BMW plans to replace the driveshaft for free and the recall should start on January 8 next year.