I just rented last weekend from JFK as a city resident. They put thru a hold of the entire rental cost plus $250 on the credit card for a 3 day rental. When I returned the car they actually gave me a receipt for a charge of only two days though the return was 2 hours early on the 3 day reservation.

So far the hold for over $300 is still there and the $70 charge has yet to show up but it is only Tuesday.