@FlyingFox
An enclosed cockpit would not work for a number of reasons. Cost is certainly one, but there are fundamental design problems. What if the canopy becomes damaged by dirt / dust / debris? Do you want to look out a racecar at 185mph with cracks in front of your eyes? In case of rain - visibility will be much worse. Try driving a Red Bull on Gran Turismo 6 in the pouring rain - there will be so much water running over the car vision will be near impossible. In case of fire and / or mechanical problem needing a quick exit, how? An ejector / release system will not work - all it takes is a driver in a car rolling or going in a violent motion to perhaps bang an ejector button in the cockpit and launch it during a crash. How will a marshal be able to get in quickly, especially if the mechanism is damaged, the driver is unable to release for some reason? You want a canopy system that can withstand sparks, dirt dust, perhaps bits of carbon fibre traveling at a velocity of 100+mph yet can be released by someone with a glove on his hand?