I have both 1999 & 2002 CNG vehicles that I recently purchased - can these qualify for federal tax credits?

These vehicles were OEM CNG vehicles. I am not sure if anyone has claimed tax credits for them. The 2002 vehicle was leased to the Salt Lake City organizing committee for use at the winter games, the 1999 was owned by the federal government and operated in California. I am using both vans for a shuttle service in Utah. I am having a hard time understanding the federal tax laws. It appears that the doentation on the IRS website indicates that they have to be newer vehicles? I purchased both vans in 2008. Thank you!