VHT compound has become a familiar term with NASCAR fans as the sticky substance has become a mainstay on the lower groove at Bristol Motor Speedway in recent years.
After an All-Star Race at Charlotte Motor Speedway that lacked much passing, the compound has been added to the 1.5-mile surface for the Coca-Cola 600 (Sunday, 5:30 p.m. ET on FOX).
In the opening practice on Thursday at Charlotte, drivers got their first test of the substance at a speedway. Although, it was a limited one as most drivers ran mock qualifying attempts for the hour and a half session.