I did the email thing when special ordering our new 2013 X3. I got it for $400 below invoice. It was $2650 below invoice if you count the rebates.
They all want you to come in, discuss on the phone etc. Say no and insist on getting a price via email. Then take that email and get counter offers from other dealers. I had 3 dealers underbidding each other towards the end. It works better if you have many dealerships around you.