In 1978, American John Guanci began manufacturing SJJ1 sportscars at his company Guanci Automobiles Inc. in Woodstock, Illinois. This car had an elegant appearance and dignified equipment. A 3.8-liter Buick V6 engine with a turbocharger served as the drive for the mid-engine sports coupe designed by Bob McKee. The car was initially priced at $63,000. Later, the GRP coupe was fitted with a 223 hp 5.7-liter Chevrolet V8. Just a few examples of it have been manufactured.