I never heard that 10 day thing either, sounds very suspicious.
Kind of looks like the dealers some how got the idea of the "10 day" thing. I would assume it was a bad rumor and they jumped on it or the administration gave them the idea. That "10 day" thing seems to be on the internet in several of locations all stemming from dealers.
example:
Ziepke is happy with the program, even if getting his money from the government has been slower than the 10 days originally expected. "We're still waiting for our first check, but we have faith." So far, it's about $100,000 worth of faith, but Ziepke still treats "Cash for Clunkers" deals like any other.
http://www.wowt.com/home/headlines/53190937.html