re: Can a dealer give you a trade in value without seeing the car in person?

They certainly can. I just bought a vehicle 2 weeks ago and employed this strategy. I would ask for a range, which will probably be on the low side. But all it really takes is one dealer to give you a fair quote, then you have your bargaining chip. Provide VIN, tire condition, color and overall shape car is in. KBB actually has a tool that can tell you, good, great, fair, etc based on a survey.

I would also say that it helps to know exactly what vehicle (including trim level) that you are looking for, and request an OTT price. If buying New, True car - Clean Trade (as per NADA) is a good aiming point. If you get a quote you are good with, bring that to a dealer and don't budge; even better, make them beat it.

After this purchase, I am now convinced (If I wasn't already) that email negotiation is the only way to go. Know exactly what you want, know the dealer cost of that vehicle, and you won't get screwed.

Final point about Dealers, if buying new, I wouldn't get too hung up on color. Most of the time, they will quote you on a car that isn't even on the lot. I showed up to buy my vehicle, and the white one wasn't even there, so I made them give me the deal I wanted for a silver with more options, for the same price.