I can only reflect on driving roughly 100 miles across Central Texas with no windshield. The reduction in frontal area certainly seemed to make my TR3A much quicker, especially acceleration at highway speeds. Worst hazard were approaching 18-wheelers. Their air streams seemed to vacuum the road surface of very mote of dust & fling them all into my face. Brooklands windscreens would’ve been most welcome, as would a leather balaclava. Blessed I was, it didn’t rain.