Well, the lad i concider my best mate of many years... i did, but never will again...
Once upon a time we did a "you can have a go in mine, if i can have a go in yours" i explained that he must not do anything retarded.... first thing he did was a J-Turn.... i went ape shit.
Kind of related.... borrowed him a set of wheels from my Yaris T-Sport, that were in excellent condition and with near new tyres, when he was struck by hard times... wrecked the tyres through burnouts, hand brake turns and generally driving like a tool... wouldnt replace them.
Then allowed him to borrow my Yaris T-Sport (the car itself) for a couple of months, as i had nowhere to store it as i had 2 other cars, and out of kindness allowed him to run it at my expense (except for fuel). When i got it back i found the airbox had been partially disconnected, because that "made it sound better" and there were two sets of golf clubs in the boot... the boot panels were wrecked with scuffs and scratches.... again i wasnt happy...
Then i was asked if i could borrow him a set of MR2 wheels, again perfect condition with next to new Eagle F1's fitted to them. They were returned worn to the canvass... again... refused to replace....
And i recent times he wondered why i wouldnt let him take my Volvo for a spin...
That person in particular will never borrow or drive anything of mine again, and has actually made me loose trust in others!
I will let the missus drive the car, and one or two others, but 9/10 i will be sat in the passenger seat!