I did this a while back, but thought I would post it here. It started out as a Hasbro GI Joe jeep. Only the main body is from the original toy. The grill, bumpers, windscreen, canopy rails, seats, etc. are all scratch-built. Pretty much every little detail was shaved off the original toy and replaced. It's also RC and has working headlights:
http://www.ryannagata.com/otherstuff/16-wwii-jeep/
http://www.ryannagata.com/otherstuff/16-wwii-jeep/