Either you trust 'em or ya don't. Good for you.
But, share this story with him:
At my senior prom, cars had just been invented. . . . wait no,
Once upon a time, there was a slightly geeky but otherwise likeable young prince(one of my buddies)who borrowed his uncle's brand new Vette and drove it to his senior prom. His uncle made it very clear to the young prince that if anything happened to the car because he was screwing around, the young Prince would be required to pay for any damage. He drove the car very carefully all night, obeying all the laws of the kingdom, until it was time to leave the dance. The young prince was very proud of himself, because unlike the rest of us, . . .I'm mean the others at the dance, he had abstained from getting hammered. To celebrate his sobriety, he decided one little demostration of the power of his uncle's car wouldn't hurt anything, so he dumped the clutch in the parking lot and burned a perfect 360' doughnut. All the young drunks, I mean young men and women in the parking lot were most impressed, and we. . .(damnit), I mean they whoopped and hollered, and encouraged the young prince to "doit again, doit again!!!!", so he did. Unfortunately, the second doughnut did not go as well as the first, and this time the young prince plowed the front end and driver's side of the beautiful car directly into a very large concrete light base, which did aproximately $14,000 damage to the car (which was a ton of money in 1983). The young prince's uncle happened to be the unforgiving type, and true to his word, required the young prince to pay for the damages rather than turn the claim into insurance. It took the young prince almost 4 years to pay off the damages to the car. As a reminder to the young prince, his evil (and pretty twisted, if you ask me)stepfather mounted the destroyed front clip of the Vette inside the family garage where the young prince used to park his car before he had to sell it, since he couldn't afford to pay for his own insurance, and pay for the damage it had done to his uncle's car. And it stayed there the entire 4 years, with the evil stepfather even requiring the young prince to wash it periodically if it became too dusty and dirty.
The moral of the story: If you borrow a powerful sports car, and you know the owner wouldn't let you do what you are thinking of doing, DON'T DO IT!!!!!!