Does anyone know what sort of pen or marker is used to write on the vehicle windows at car shows. I have noticed it at many different shows but never asked.

No one will be writing on your windows Dain. You will be given a placard that has your registration number and class that you are entered in. The placard needs to be displayed on your dash

Sorry for the misunderstanding...i am not registered for the show this weekend...didn't make it in time...i will be in the area with my car and have my 2002 Saleen Extreme for sale. I wanted to put neatly put some details on the windshield without junking the car up with signs, flyers etc...I have seen the neat marker writing on the windshield at several shows...just didn't know what it was...

You need something like drag racers use, like this http://www.jegs.com/i/JEGS/555/1035/10002/-1. Maybe check out any speed shops around your area to find something like this?