Former Formula 1 driver Sebastian Vettel was "surprised" by Christian Horner's exit from Red Bull Racing earlier in the year.The German driver won his four championship titles under the leadership of Horner at Red Bull between 2010 and 2013. He claimed that the Briton will have "left some big footsteps" for new team chief Laurent Mekies to walk in.Horner was replaced as Red Bull Racing CEO ...Keep reading