This looks like one of the Corvette America 4-doors built in Pasadena, California by California Custom Coach in 1980. A limited production run of 40 or so was planned, but in the end only 5 or 6 were actually made. They've appeared on this site several times and occasionally one turns up for sale. Monogram even offered a model kit of it. They were reportedly built by cutting two cars in half which, when mated together, extended the wheelbase of the vehicle by 30 inches.