BERLIN, Germany - Sebastian Vettel may have quietly added two years to his Red Bull contract.In 2013, while already tied to Red Bull in 2014, it was announced that Vettel had extended his deal to include 2015.Team boss Christian Horner said at the time: "I hope the relationship will go beyond 2015, which is already some way into the future."LURE VETTEL TO MERCDespite the depth of Red Bull's early-2014 pre-season technical crisis, it appears Vettel may indeed have stretched his tenure with the team even further. The news emerged as Red Bull director Helmut Marko and Mercedes' Niki Lauda light-heartedly discussed the future during a Sport and Talk programme on Austria's Servus TV.Marko jokingly revealed that team chairman Lauda was keen to lure Vettel and car designer Adrian Newey to Mercedes. He said: "Niki comes every day and asks if Newey and Sebastian will go." Lauda replied: "But you always tell me that Newey and Sebastian have contracts until 2017." Whether the references to 2017 revealed some impending announcements, or were simply a joke between Austrian friends and rivals, was unclear.