4Gear R5 S'cool Bus (Yellow) Carffiti. Auto World's new 4Gear chassis is based on a classic extended "pancake" design. It features an extra gear on its lengthened power transfer plate. The extended wheelbase and narrowed rear end fitted with gigantic dragster-inspired wheels make it perfect for custom applications and totally wild specialty vehicles! And that's not all... Flip the chassis over and you'll find two neodymium traction magnets to make these dynamite racers grip the track for super high speed racing excitement!