A plan to require a deposit from owners of U.S.-registered cars entering Mexico was revised and will now go into effect Dec. 1 instead of Nov. 1. The deposit can be left on a credit card rather than the original plan to take cash only, and can be refunded at any border crossing. The rate is $800 for 1999-2000 models, $600 for 1995-1998, and $400 for 1994 and older. The deposit is an attempt to prevent U.S. cars from being sold illegally in Mexico.