That is a great time....
A 2010 Dodge Viper ACR holds the record for a factory production, street legal vehicle at 7:12:13. Both Viper and Corvette will be back to attempt to reset that record.
It's down to tire choice now.
If you are using the current michelin pilot sport cups with tread shaved to 6/32, you could probably go fast in a porsche 914.
There is a lot of money in having the fastest car and fastest tire so I would think there is a lot of money changing hands and lobbying by manufacturers to get a quasi race tire certified as "DOT approved".
It's only a matter of time before someone brings some hoosiers that sports a dot stamp runnning a treadwear number of 40 where the michelin pilot sport cup is now 80.....which I consider unacceptable on the street since I see them get replaced every oil change on a non-track driven car.
Eventually, there will be a spec. of tread and compound that will be considered "mininum" concerning treadwear in which the lap time is considered official or not because we're already seeing accidents here in florida on pilot sport cup equipped cars because of the frequent rain.
That said, the lexus lf-a does it only 2 seconds slower on a tire with a treadwear or 140.