To export a vehicle, grab a vehicle able to export (usually called wanted at the board near the crane) then park it near the magnetic dockside crane in Easter Basin, San Fierro. Enter the magnetic dockside crane, then move and lower the magnet to pick up the vehicle you want to export. After attaching the magnet to the vehicle, maneuver the vehicle using the crane to the tanker. (Alternately, you can simply drive the vehicle up the ramp leading to the boat; however, some vehicles are too big or long to drive up the ramp.) Carefully drive the car onto the marker. A message will then display that you have successfully exported that vehicle. You will receive money, depending on the type and condition of the car.
Money is deducted for any damage, so it's a good idea to take the car through the Pay 'n' Spray behind Wang Cars, to repair damage. Alternatively, fix the cars in your garage to save money. It's a good habit to do this with every car obtained for the mission, even if no damage occurs while Carl is driving it, as unnoticed damage can occur to parked and computer-driven vehicles off screen before Carl obtains them.
Huntley - Parked near the Driving School. (Note that the Huntley doesn't regularly spawn at the Driving school if all tests have been completed to gold, as it spawns where the Hotknife spawns.)
Mesa - Parked next to a building at the base of Mount Chiliad (when wanted for export).
(Note that vehicles will only spawn in certain locations if it is currently on the board. For example, the Euros will only spawn at the The Camel's Toe if the player is on the third list of cars and has not exported a Euros already.)
Reward
Cash is awarded for each car successfully delivered, ranging from $10,000 to $135,000 (with cash deducted if the vehicle is delivered with damage). The player will recieve a large cash bonus for completion of each of the lists, ranging from $100,000 to $200,000 per list.
Delivering a vehicle will unlock a new vehicle being made available for import on certain days. These vehicles range from additional copies of vehicles delivered to the dock, to rare vehicles Carl may only be able to obtain via import. These vehicles may be purchased on certain days of the week only, and may be bought during or after completion of the sub-mission by returning to the blackboard. Vehicles purchased appear on the deck of the freighter, requiring Carl to either use the crane or attempt to drive them down the ramp.
Exporting all 30 vehicles is a requirement for 100% completion of the game.
Most of vehicles that you buy/have to deliver will have a rare license plate. Many of them seem to be names and initials, presumably of Rockstar employees. Here are many variants and translations: