Kimi Raikkonen hints at Lotus walkout . Raikkonen unhappy about not being paid yet for 2013 season . Score: 6 Sebastian Vettel fastest in practice at Yas Marinas .
Kimi Raikkonen hints at Lotus walkout . Raikkonen unhappy about not being paid yet for 2013 season . Lotus fourth in constructors ' championship heading into final three races . Sebastian Vettel fastest in practice at Yas Marinas .