Salespeople in US are experts in in-person verbal negotiations, just like the sellers on a Istanbul's Grand Bazaar. If you let them, they can and will employ all the dirty persuasion and negotiation tactics that you may or may not be aware of. Anything that is not illegal can and likely will be done to you. For example, not providing the complete information about the car is not illegal, lying is (sometimes) not illegal. Stressing you out is not illegal. Adding overpriced optional features to the car and not mentioning that they can be removed at no cost is not illegal. Making you wait a lot for no reason to make you tired is not illegal. You get the idea. It is very important to have a verbal communication for using full power of negotiation skills salespeople have. In-person conversation is the best - it is possible to read body language, easier to build rapport, but phone works well for some scenarios, too.