Here's another perspective for what it's worth.
I worked with Paul Young Jr. in his VW at a previous driving school. He had planned to drive his father's car, but it had mechanical difficulty. (This presents yet another exception to an alternate policy-he early registered and is an active member with our club.) Although the car didn't replicate the performance of a Porsche, his execution of the skills displayed his driving ability. He is a competent autocrosser who drives well and within his limits. Lucky for me, I've only been instructing for 2 years, so I didn't have to bring myself "down to his level", I was just there!
As for my student in the mini autocross on Sunday... I volunteered to instruct him. Eric requested me to work with him because he felt comfortable with me. I agreed to switch students with another instructor to oblige his request. (Although the original student I was assigned was a girl with a red 944-perfect match guys!) This kid was in my skid pad group Sat morning and was full of energy, for sure. Don't you think he noticed that everyone was laughing at his car? His father had just got his own car back from the shop the day before. It had a much larger engine and other modifications made that made the father feel uncomfortable in regards to driving the car Sat. This was conveyed to Eric. He was offered to repeatedly drive the P car, but was smart enough to know that it was more than he could handle. Part of the challenge was just breaking through to this kid, it really didn't matter WHAT he was driving. By the way, his car was not unsafe- I assumed it passed tech, like all the other cars. I asked about tires, oil etc and had him clean out loose items, just like I do with all of my students. I wanted to change his attitude which I can attest, was successfully accomplished. Eric learned about what A car can and can't do. He learned that over half the instruction is thinking about and "getting" the exercise and executing it, at some level, on any vehicle. To be honest, Eric was in better control of his vehicle than one of my previous PDS students who drove a CGT! I learned a lot about students. I drove with Ryan Mistak and can tell you he had HUGE improvement in his ability to drive a performance vehicle. I knew absolutely NOTHING about his Mustang. I think I did one lap to show him the line, but I could communicate to him what I wanted him to do and he would keep trying until he achieved the desired effect
I know that this thread is about policy now. I just wanted everyone to have another side of this story. Hope this helps in the decision making.