Can I test drive the cars?

I suggest doing a very thorough check due to you not being able to drive them. Maybe bring a mechanic, a code reader etc

You can start them though

Nop, u can not . Only check them out But not drive them..

Yes

No but you can start them and bring a mechanic with you to check out the under carriage, struts, tie rod ends, etc.

No, you can start the cars, and check everything but cannot move the cars.