So far, I never face any problem for test drive. What I did was hold the HSBC check book on my hand
Car and human are the same, both are as good as their last resume. You can opt for bringing a specialized mechanic to check the car before you dig your wallet, or keep the downpayment until the car send to a specialized workshop to check and have green light from mechanic (on your cost of cause). There is no such thing as NO for a businessman. You just need to show the money and open your mouth. As long as it is not ridiculous, normally ok. Mileage, lady driver, and etc all are busted myth since last 2 decades. If don't do 18KS, how a loktor can determine how much Hep B antigen you are having? Or, women with big and round bump must be easier to get pregnant (aka Ho Sang Yeung)?
A car condition only can be told after checking and diagnostic. Now businessmen even open a specialized workshop and give you a warranty on the used car which par to a new car.
But to be fair to everyone, there are too many people request test drive and after test go else where to test drive just for the sake of spending the free time. I also did that but my friend's father own the shop la