The idea of booking the internet salesman ahead of time for your test drive is good, though, I never thought much of getting one involved until I was ready to deal. Updating car-buying procedure in my head....

You tell them you have a few more cars to test drive before discussing a deal. They know you are internet-savvy since you contacted the internet group. He either believes you that you are going to go test drive other cars or he believes you're going home to start an internet bidding process. Either way, he's going to try to cut you a deal so you'll either skip the other drives or not bother with getting other prices. Letting you walk is not a good option.