The following article was posted to Kinja earlier today. It talks about the Laurel Hill Tunnel and how it has been used to test NASCAR and IndyCar vehicles. The article also states that it will see less use due to regulatory changes made by the governing bodies for those sports.
http://kinja.roadandtrack.com/the-secret-racing-test-tunnel-no-one-wants-to-talk-abou-1678596274/+ballaban
It will be interesting to me if the tunnel falls out of use again if it can't be used as often as it once was.
EDIT: Fixed the link. Thanks!
The link is broken. Remove the second http://.
Heh, when I first saw this thread I briefly thought a mod had moved my post into its own topic.
https://www.aaroads.com/forum/index.php?topic=419.msg2033413#msg2033413
The article is quite the interesting read and I do agree that I hope it's continued to be used.