Found this comment following an article on API. Here's the quote:"the A. P. stands for Allen Paulsen, under whose colors Indy raced. You've seen them on many great horses, including the one and only Cigar. Red White and Blue, with the stylized "AP" on the back.the Indy part I kind of have to guess at, for I don't recall conclusively. I believe it had to do with either the INDY 500 or a Navigational point of call used by airmen. Paulsen came by his wealth by developing airplanes - Gulfstream, I believe - and he would name his horses after these navigation points around the world. Cigar was one such point." points around the world. Cigar was one such point."