Over 20 people have driven my car, and driven it hard. Probably a dozen or so have driven it down the track. I've let people borrow it for a week, completely unattended.
Quick Story - A friend of mine lost power at his house, and his basement was starting to take on water. I told him I'd meet him at Lowe's and help him pick out a generator and get it set up for him. The generator wouldn't fit in his SUV. Random kids in a truck show up with nothing better to do. I offer $20 to bring the generator 5 minutes down the road. I tell my buddy to ride with the generator so they just don't drive off with a $500 generator, and in case we get split up.
Then I ask the kid that's with me - you got a license? ... Long story short, the kid driving the truck shit his pants when he realized that it was his buddy flying down the road in my car and not me driving. If I was that kid... it would have made my year, and would have effected me for the rest of my life. As the guy who made it happen... it had the same effect. You never know what kind of impact you can have on someone's life with a little bit of kindness, and a total lack of responsibility.