Four-time Formula One world champion Sebastian Vettel and Mick Schumacher will join forces again and compete for Germany at the annual post-season Race of Champions motor sport event. Vettel won four F1 titles 2010-2013 and retired from the sport after the past season. Mick Schumacher, the son of record seven-time world champion Michael Schumacher, has appointed Mercedes F1 team reserve driver after not being retained for a third year by the Haas team. Organizers said that Schumacher would also compete in the indivudial event of the Race of Champions which brigs together drivers from various m…