I've always wanted one in the car, you never know when an emergency will arise. including a seat belt cutter - shards. Actually I was going to leave the hammer in the car but that solves the problem :) - The air pressure gauge is great, put it on the tires and it not only shows our measurements but also talks to them. Actually helped me when one of my tires was still low and after taking it to the service center they found a small nail. Analog, which I never had, could not provide accurate readings.