Training a 9mth old

Question
My GSD is the smartest dog I've ever had. She has an invisible fence and is let to run free every day. The only issue I'm having is when I get home and pull into the driveway she comes running in front of the car (no fear yet) and jumps on the door excited for me to get out. My car is getting scratched and I'm afraid one of these days I won't hit the brakes fast enough and I'll hit her.  How can I train her to go sit on the front step or something?

Answer
They really are smart aren't they Sarah? :).
Do you have someone who can help you?
If so, get them to leash your girl, and wait with her away from the front porch. When you begin to pull into the driveway, blow the horn. Have your helper immediately run with your girl to the front porch and have her sit. Let her do it in a very excited manner. The instant she sits on the porch have your handler give her a treat, and hold her there while you get out of the car. When YOU get to the front porch give her a treat and lots of praise. Repeat and repeat until she will go off lead with the handler to the porch and sit when you pull in and blow the horn. ALWAYS blow the same number of times and the same way. Once she is doing this consistently with the handler, have the handler go inside the house and see if she will go on her on when you blow the horn. If she does, the INSTANT she sits have your handler come out and treat her. Repeat and repeat until she is doing so consistently you may have to go back to the beginning a few times, it's a complicated task. When she is consistently sitting on the porch when you blow the horn have the handler remain inside the house , pull in, blow the horn, get out of the car and go IMMEDIATELY to the front porch and treat your dog. From them on ALWAYS blow that horn when you pull in and ALWAYS treat immediately, don't wait and get things out of the car etc and don't ever ever forget!
Cindi