We just picked up our Challenger this past Saturday, specs in my sig.
First, I feel I should mention an awesome program from USAA that anyone can use. USAA has a "TrueCar" program where you can get the USAA price without being a USAA member provided you use a participating dealer.
Go to http://www.truecar.com
, select the year, model, and options you want. It'll tell you who the local participating dealers are. Then you can print out a certificate and the price is guaranteed, even if they don't have that exact car in stock the discount applies to any other color or options. In my case, the TrueCar price was $1500 below invoice.
So, long story short, my local dealer doesn't participate in the TrueCar program and they were the only one within a reasonable distance that had this car. So, I ended up getting it for $1250 below invoice, or $250 below invoice plus a $1000 rebate on top.
Ultimately there was virtually no haggling involved, got it for below invoice, decent APR, and they beat the other dealers on our trade by about $1000. All in all, I really couldn't be happier with the deal.
Anyone looking to buy new should definitely try out TrueCar.