I found these at TRU today. They are designed almost exactly like the Zip Zaps, but are bigger and instead of slots, the bodies just press fit over the chassis. They even have the same interchangable hubcaps. You can buy the motor and gear upgrades, and also extra bodies. The bodies are really nicely detailed too. They have Mini's, EVO 8's, Stangs, and others and in different colors.
Here is the future site:
http://www7.toysrus.com/superslicks/ss_comingsoon.cfm