it should take place simultaneously...

your existing car will be treated as part of the "down payment", for you to complete this transaction. I presume you still have your existing car as of this point, at least not until 周6. Once the title is transferred (周6), the dealer will then payoff your loan. Different financial institutions have different procedures. CapitalOne may wait 5-10 business days for the check to clear, prior to forwarding the original car title with the signed off release. Right now, even the dealer said they've already taking care your loan, you have no way to confirm this, until you call CapitalOne. My guess is CapitalOne may not be able to give you the final words until the check is cleared, which could be couple weeks...