You may be in the wrong game mate

If someone wants to buy a car, they want to know about it - or should do. If you sell a car for 500 quid or sell a car for 50 grand, to the buyer it is what they can afford and need it to be reliable and useable otherwise why buy it.

If anything, a person at the lower end of the market has to be more careful as they are unlikely to be able to afford to repair the car should they buy a lemon

As for asking questions via email, whats wrong with that, the buyer can email you at anytime and you can reply at your leisure with all the facts, rather than you getting calls whilst your busy and not being able to give all the details they want.

I admit some people ask stupid questions but what has been asked is really just the norm.