The whole situation sucks. In my personal experience there is no reason to "enjoy" a customers car after you have completed the work the mechanic is supposed to be a professional and joy riding is not in that job description.
I try to drive customers' vehicles as little as possible. I have been rear ended in a customers car less than one mile from the shop while sitting at a red light. Although it was not my fault and I was performing a legitimate test drive, I still felt crappy about it and wound up giving all the work I just did to the customer for free. Although the car got fixed by the same body shop that I let work on my personal car and the customer was totally happy (and is still a customer, now just a better one) I would have rather it not happened at all.
It is from experiences like this that when I feel it is nessissary to drive a customers car outside of my normal 1-2 mile test route I will usually contact that customer and ask permission. If I feel the need to "enjoy my work" I have no problem asking the customer if they will go for a ride with me to give the car a beat down run. Usually they agree without hesitation but it is not a thing that is done often or without them sitting in the passenger's seat.
Basiclly, everyone screws up at some point or another, its how you deal with it that makes the difference. If the owner can find a way to make everything right and the customer is satisfied that is great and hopefully they (as a shop) can learn a lesson from this.
And Tony, I am gonna let that vette have it next time you bring it by so thered better be a full tank of premimum and a fresh set of tires on the thing!!!!!
J/K!