Rahal Letterman Lanigan Racing. Honda. GRAHAM RAHAL. #15. Graham Rahal is in the peak of his IndyCar career, and he is currently driving for his father’s team, so there is no reason to believe that he will end up anywhere but the seat of the #15 Rahal Letterman Lanigan Racing Honda in the 2018 season. He has been the top finishing Honda driver in the championship standings in each of the past two seasons, and he is in the thick of the championship battle this season yet again as the only Honda driver with two victories, a total that is tied for the lead among all drivers.