As for trying to negotiate over the phone, I wish you the best of luck with that. Some dealers might play, but most wont waste time on it anymore.
I've found this to be mostly true. You'll get a price out of nearly everyone over the phone, but I'd say 20% are actually giving you their "best" price (or something close to it). The rest are quoting thousands over invoice, which is, I assume, their standard "here's a price over the phone" price.
It's still worth it to shop around via phone in my opinion (vs wasting a ton of time driving around). Between small talk and other BS, you can spend hours at each dealer.
If you can, talk to sales managers on the phone, not the bottom tier salesmen. Know what stock # and VIN you're interested in, be specific and to the point:
Hi, I'm looking to buy a ____ like stock # ____ immediately and I'm shopping around for the best pricing. Minus factory rebates etc. can you quote me your best price on the vehicle?
You'll at least get a feel for how each dealer does business, and pricing. Then, you'll be armed with more info when you actually go to visit a dealer or two that gave you good quotes and seemed like low/no BS. Save the true negotiating for at the dealership.
I've done precisely this several times, and recently drove 1.5 hours to a new dealer just because they were the cheapest by far and had no problem giving me their rock-bottom, best price over the phone with no sales BS. I'm so happy with how I was treated I may literally drive there for service.