When I bought my Nissan Altima SL a few months back I sent emails to the internet salesman at 3 locations asking for their best price on what I wanted. My criteria was exactly what I wanted, and in their language, taken from their own website so there was no confusion.
Of the 3 figures I got back, I worked with the 2 lowest figures letting each know I was seeking bids from other places. I was able to quickly zero in on one dealership, fine tuning the deal after a test drive. It was painless, I'm told internet salesmen don't require the same profit margin as the floor salesmen as they deal in volume. I got the car at a great price, they made some money, I got the best deal possible.
I had already prepped my salesman with the info that I have walked out of the F&I office in the past and will do so again if I am pressured on GAP, Extended, etc. It was a zero finance deal through nissan so the interest rate wasn't a factor. I was in and out in 15 minutes because the F&I guy was already informed I wasn't interested.
I would recommend using the internet if you're buying a new car.