They are random, as I found out when my PS3 crashed moments after getting my 5 cards on the second day. Auto save does not kick in when you receive the cards. I had looked at them, and as I came out the Museum the PS3 crashed, I had to bomb out the game and then when I went back in I received a different 5 cards and found that the 5 I had just looked at had disappeared. So I'm guessing that means when it gets closer to the September 2011, if you don't start getting the cards you want, all you need to do is keep restarting the game before it saves.
On a side note, my first 5 cards exposed a slight glitch with the Lotus No. 11 card. I got two of them - not one card with the number 2 in red - but two physically seperate cards with number 1 next to them, but they are both no. 11. In the main index though it only says 1 next to Lotus, and I did get 4 other cards. Gotta wonder if I "give away" the one card will both disappear, or just the 1...
