Find starting positions for NASCAR races at FantasyRacingCheatSheet.com as of 2015. This website organizes the starting positions of all active drivers by track. It also displays the overall average starting position for each driver.
Find information about the schedule, standings and drivers at NASCAR.com. The starting lineup for each NASCAR race is listed along with the car manufacturer, best speed and best time. This website also has a fantasy league and other games related to racing.
General sports websites such as SBNation.com post the starting positions for individual races -- usually within articles about the race. These articles also give some background and context to the race and the drivers.