ir_fuel

Yes, but as everywhere, I guess everyone draws the line where they want concerning their own safety. On the average track day I see people driving in jeans and t shirts. And wearing cotton clothing underneath your racing suit isn't really ideal either, as the cotton soaks heat and you will basically get cooked by the sweat steaming when there is a fire.

You have people doing track days with a street car using 3 point belt, an open face helmet, in jeans, t shirt and regular shoes. You have people doing it in a fully caged car, with 6 point, hans, and fully FIA compliant clothing underwear included, and all variations between those 2 extremes.

Personally, I am of the jeans and t shirt type atm, using 6 point + HANS and closed helmet (drove with open face helmet once, I hated it, never used it again).
Since I have the Cup car I have a fire extinguisher that is armed every time I drive the car. Maybe it's time to "suit up"