I'd have to save up for 10 years to afford a ZR1 as-is. And that car will NEVER....EVER see its potential under my piloting. Worth spending more for 9 seconds around a track I'll likely never visit in real life? Not at ALL!!
The ring is unofficial, as there is no authoritative body overseeing a manufacturers runs, and the lap times are no more important that "mine is bigger than yours" arguments.