It's very similar to having a stretchy electrical tape with better adhesion. We used to use it to wrap heater wires around pipes in commercial aircraft. It would be really good to repair a leaking hose, or even wrap some an electrical connection to waterproof it, but I'm not sure what other uses you can find for it. I think it's rated to a fairly high temperature, so I wouldn't worry about leaving it in a car. They arent' kidding when they say it fuses to itself, it becomes like a one piece silicone covering, so unwrapping it is out of the question, you need to cut it off. But it doesn't stick to whatever you apply it to, so there's no residue to clean off afterwards. Go to Walmart and look in the plumbing supplies, you will find an identical "plumbers" tape for about 1/4 the price.
I usually leave it in my toolbox, but really haven't needed to use it for anything. If you're thinking for an emergency kit, I think Gorilla tape or duct tape would be more versitile.