The best way to do it is to shoot the vehicle driving by -- then shoot another video of exactly the same shot (lock down your tripod) with no vehicle.
Put one video on the Video 1 track and the other on the Video 2 track directly above it -- then use either the Crop tool or the 4-point-Garbage Matte to "hide" the part of the video that shows the truck driving out from the other side of the tree.
I essentially used the same effect to create the illusion that I was talking to two other people (all played by me) for my "Cool Tricks" book.
I will follow your advice. And thanks for the quick reply.