In 2012, Mercedes-Benz delivered all the rights of V12 engine development to AMG for future V12-model vehicles. Starting the 2014 model year, M277 has been extensively redesigned and updated their top-of-the-range V12 engine to better conform to increasing emission standards in Europe and the United States. Despite the basic design being more than 16 years old (M137), the new engine has enough modifications and sporting character that the engineers felt it warranted a new engine designation. According to Mercedes-Benz, the most important features of the new engine are: