err... if I remember right.. air drag does play a roll at all times but, its most effective when the vehicle is NOT on the ground. Changing friction is possible in multiple ways. I never messed with negative values though. As far as I remember, all items in empires have the same grip except jeep tires. I played around with multiple material values that are fun. Did you guys know you can change material values to make Jump/Fall tiles? I changed cement to give 10X jump boost. It was great... until I realized the personal servers does not have parachutes and I died. You can also make vehicle boost tiles with materials too. However you will still hit the max speed wall.
The interesting thing is that is actually fairly easy to do. :\ The hard part is making an interesting map.
