I don't see any of the usual blocking/cribbing under it like most clay models have. It appears to be a rolling prototype. The Panther emblem is on the fender and a script on the trunk that apppears to be panther as well, even in all lower case letters, like the production models.
VERY close likeness to what was put into production 10 months later.

Calif Hancock Station with a '69 Grand Prix in the street.

----Those can't be gas prices, can they?....Bill S