If you want to be ready for any car emergency, assemble your own car gadget collection. These tools will become your new best friend as you pull over to the side of the road and need to jump start your battery or read the tire pressure. Pick up a pocket-sized battery with jumper cables. A digital tire gauge removes the guesswork from hard-to-read tire pressure scales. A Bluetooth FM transmitter plugs into your car and plays music on your phone. Head to eBay for more awesome car gadgets!