When buying a new car, is the price negotiated when ordered, or upon the arrival of the car at the dealership?

When ordered. At least it was in my case. I wasn't going to make a deposit on a car (refundable or not) until I had the details hammered out in advance.

My dealer has always told me they'll give you the lowest price from the day you place the order until the day you take delivery - so if say a month after you order, GM comes up with a new offer that ends up being chaper, you'll get that. If they come up with something more expensive, they'll give you the original deal you negotiated.

Can't wait to put that to the test when I pick up my car. Dealer tried to put me on 7.1 APR for a lease...when it is 6.1...i ordered the car anyway but when the time comes to pickup the car, I will give them hell! That 1% works out to about $1000 savings for me....