It doesn't matter what his pay was, it's his right to keep it confidential. There's a reason why in business there is negotiation based on your value and leverages. Taking past pay as reference not only gives unfair leverage to the company, it also slows and stunts the growth of the employee. I seriously don't understand why employees would defend this. Negotiation is important, it is part of business. Why make their job easier and limit your own growth?
Exactly. Based on that analogy, what matters is what the car is going to bring you. How much the car is going to cost you should be a negotiation between you and the dealer.