How old to test drive alone.

I use to be a salesman, (i know, Ive heard it) the real reason is not ins. it's cause it is very revealing to the salesperson of what you think of the car. and is a very good time to get you saying "YES" and that means $$$$.
You would not believe the phsyscoligy that is used and tought to sales people in selling cars. You gotta believe me it is intense. would you believe that when on a test drive if you make only right turns you have a far better chance of selling to the cust. than if you make left turns. think about the test rides with salesman they tell you where to go and it's always right turns not left.
I'll stop now, but it is hard to do without a salesperson unless they are new