Back in the day the "American Invasion" upset a number of the touring car purists, with attempts to neuter their dominance through technicalities in the regulations.
It took me a few days to remember who ran an Impala and when, but Dan Gurney ran a nearly stock '61 409 4-speed Impala in one of those races. If I remember correctly, Gurney in the Impala beat on those Jags until a wheel failed, ending his race. They wouldn't let him enter the car in to another race.