No guarantee of 2015 Mercedes challenge - Vettel

Sebastian Vettel has suggested Red Bull's current rate of development is not at the level it needs to be if the team is to enter 2015 on an even keel with Mercedes

Source: http://en.espnf1.com/redbull/motorsport/story/166685.html?CMP=OTC-RSS

Christijan Albers Michele Alboreto Jean Alesi