Found it - someone had posted this answer in the Xbox 360 board, and they got it from Wkipedia. (It was right in plain sight in the General Store - I don't know how I missed it - LOL!) Got all ten now - 7 from Vegas and the three DLCs.
"Explain to me and tell me, how you got this need for speed?" He laughed and said, "It just might be the next best thing to love!"