1980 saw the arrival of Excalibur’s Series IV, and it brought about the first real change in appearance for the Milwaukee, Wisconsin marque.

While the new model still evoked vintage Mercedes-Benz, this time it emulated the 500/540K series, rather than the SS/SSK.

The ladder-type chassis, especially unchanged relative to the Series III's, was stretched by a further 13 inches.

With four-wheel independent suspension, front and rear anti-roll bars, four-wheel disc brakes, a Positraction rear end, generous 30-gallon fuel tank, and all-stainless dual exhaust system, the Series IV was undoubtedly the most refined and luxurious iteration of Brooks Stevens’ automotive vision produced to that point.

These Series IV cars derived their power from a ubiquitous 305-cubic-inch General Motors V-8 engine—as seen in the contemporary generation of Camaro, Corvette, and Trans Am—which delivers 155 horsepower to the wheels via a Turbo-Hydramatic 400 automatic transmission.

Although performance continu...