I love this. Couple of notes - lighting inside and towards the far wall of the tunnel and darkening the room should improve smoke visibility. Also I am sure you have done this but the air needs to be as laminar as possible entering the tunnel - at a smaller scale you can achieve this by putting a heap of bundles of straws (5cmish) the same size of the tunnel at the intake. You can then take your smoke wand and put it in from the top or side, sealed with silicon etc to provide minimal interference while being able to position it as you need. Really cool project. All you would need to add is some scales - you can get away with two cheaper digital scales end to end - one for front and one for rear wheels although ideally the skyrc scales would be what you want. This allows real differential measurements and with a bit of calibration would allow you to better understand down force changes. Even running a load cell or scale at the rear to be able to calculate drag... It's all simple stuff but man it's fun. Also - a basic anemometer to better reference airspeed.