Common practice it to just lay things as neetly as possible onthe back seat and floorboard of the family sedan... sometimes tuccing it in with blankets or towels to add some padding and keep any fuel dtippings out of the upholstery and carpet.

You can make "wing bags" from cheap quilting material and even make a cover for the fuselage and tailplanes. Thes do help reduce the amount of dents and scuffs the airplane gets. They are generally not used until you get a higher value aircraft though.

You can make a rack for the aircraft out of PVC pipe with the formed foam insulation to act as padding. this type setup is commonly used for transporting odels in the back of a pickup that has a topper or tonoue (sp?) cover.

I have been known to stick the assembled model in the back of my minvan... and toss in a cardboard box (empty) to keep the thing from rolling around.

Basicly... anything that keeps the plane from bouncing around and getting squashed will work fine.