Good question Shane. The cynical side of me thinks its got something to do with the Tasman Revival F5000 series itself, where there is a heavy emphasis on race wins and championships. A later model Lola or McRae will definitely offer more chances to win a championship than an older McLaren M10. The McLaren is possibly a little cheaper to buy, but running costs will be the same. But a newer car will put you towards the front of the field, where the tv and magazine coverage tends to focus more.