Did this with the last car I purchased, I emailed every dealer within driving distance stating the make, model color, and options I wanted and asked them to provide their best out the door offer.
This was in 2004 so Internet sales were still fairly new some of the emails I received back were hilarious.
"We only sell vehicles at MSRP..."
"Oh sure we could come down several thousand dollars on that vehicle to MSRP..."
"You will not find a single dealer in this state selling that vehicle below MSRP!"
I forwarded the last guy several of the quote from his competitors....
In the end I went with the one who said they could get me the vehicle at the best price. The vehicle was inbound to another dealer and they did a dealer trade.
Before all of this I had done my research, test drove a similar model vehicle and had a good idea what I wanted to pay.
We made a small deposit via credit card that was fully refundable. A few weeks later the vehicle arrived at the dealer, I printed out the emailed quote (just in case), drove to the dealer, inspected the vehicle test drove it and finished the sale.
I handed over a check for the previously negotiated price, they did ask if I wanted a couple of other extra dealer installed items which I declined without any pressure.
It was by far the fastest transaction I have ever made for a vehicle purchase, I think we were in and out in less then 30 minutes (not include the test drive).