http://www.signonsandiego.com/bajaguide/Getting.html
Driving across
No special entry paperwork is required for your car when driving into Baja. You need to purchase Mexican auto insurance, however, which is available on a per-day basis at any of the numerous drive-through insurance outlets that dot the border area near the last exits of I-5 and I-805. These are easily spotted from the highway. Mexican insurance is also available online from Baja Bound Mexican Insurance. Their website (www.bajabound.com) allows you to buy and print out your policy before you go to Mexico.
U.S. auto insurance is not valid in Mexico. Budget, Hertz and Avis are among the rental agencies that allow their vehicles to be taken into Mexico, as far south as the Ensenada area. Mexican auto insurance is always mandatory with rentals and runs between $6 to $20 per day, depending on the value of the car and whether the insurance is for liability or full coverage. There is no deductible for Mexican rental car insurance at some agencies. Inquire before you reserve a car.
