Unfortunately he is driving in the wrong direction for the drop-off charge. Driving north is much more popular than south, for some strange reason (maybe related to all the international flights into LAX), so a lot of rental cars pile up at SFO. The charges vary by company and week, but typically it is free southbound (sometimes even the car rental is free for a few days, if they are desperate to get the cars back to LAX) and costs anywhere from $50 to $500 northbound (again depending on the company and date). The price may also be different between SAN, LAX, SNA, etc. as the point of origin.