The 1966 Trans-American Sedan Championship was the inaugural running of the Sports Car Club of America's Trans-Am Series auto racing series. It was open to FIA Group 1 and FIA Group 2 cars and was contested over seven races. Manufacturers titles were awarded for both Over 2 Liter and Under 2 Liter cars with Ford and Alfa Romeo winning their respective class championships.
The championship was contested over a seven race series. Overall winner race winners are shown in bold.
The Dodge Dart of Bob Tullius won the Over 2 liter class at the opening race at Sebring International Raceway, while the Alfa Romeo GTA of Formula One driver Jochen Rindt won the Under 2 liter class and was placed first overall.
Over the course of the championship Ford Mustangs won the Over 2 liter class at four races with Dodge Darts winning twice and Plymouth Barracuda once. Alfa Romeo GTAs won the Under 2 liter class at five races with Ford Cortina Lotus winning twice. Ford and Alfa Romeo won their respective class championships.
Points were awarded according to finishing position. Only the highest-placed car scored points for the manufacturer. Drivers' championships were not awarded in Trans-Am until 1972.
The following models scored championship points for their respective manufacturers.