Are you going to do the windows, tires, equipment, etc., in different fabrics than the body of the truck? If so, you will need to trace each of those elements onto the fusible and fuse to those fabrics separately.
There are some good YouTube tutes about working with multiple layers of fusibles and machine applique. There's also a Craftsy class which looks pretty good.
http://www.stitchinheaven.com/craftsy.asp And here's a link that might help some. It is talking about pre-fused kits, but is good for do-it-yourself fusible applique.
http://www.howtodoprefuse.com/