Sometimes locals are wrong, like the post that said you can't drive a rental car from Chile to Argentina. We did exactly that in 2004: see DresellyUshuaia.blogspot.com ChileanRentacar@ChileanRentacar.cl had better rates than Avis, the only other company that allowed border crossings, but refused to reimburse us for our replacing a defective tire that, we discovered in a remote place, had been poorly patched. We loved Mendoza and the rest of northern Argentina, which has honest border officials, friendly people, very low prices, terrific scenery and excellent infrastructure, except for some dirt roads. But we drove them. Phone us at 207-729-4001 for more information. Kindly acknowledge this post via phone or our blog. Be sure to ask rental company what documentation you must bring.