Plymouth Rapid Transit System muscle car concepts going to auction

Over the past decade, Chrysler has built a reputation for amazing custom concept cars based on production vehicles for the SEMA Show and the Easter Jeep Safari. But the company's customization tradition has much deeper roots that include this collection of muscle car concepts headed for Mecum's Indianapolis auction this May. The collection includes three Plymouths that were featured in the traveling display called the Plymouth Rapid Transit System, and a Dodge that appeared at the 1969 Chicago Auto Show.

The possible crown jewel of these cars is the 1971 Plymouth Road Runner, and that's simply because the car is completely unrestored with just 1,300 miles on the odometer. Apparently the owner of the shop that built the car for Chrysler got it back after the Rapid Transit System tour ended and took care of it until he later sold it to the late Steven Juliano, whose estate is now selling this collection of cars. Like all of these cars, modifications were mainly visual, but they were extensive. A custom nose and headlight lenses were fitted that added six inches of length, according to Mecum. The car's bumpers were removed completely, as were the external door handles. Recessed hood scoops were added to the hood, and the trunk lid was lowered by four inches to create a rear wing. The taillights were given red, yellow and green lenses like traffic lights. But the best additions were molded Road Runner head marker lights. The interior is mostly unchanged, and the engine is a stock 383-cubic-inch V8 with an automatic transmission. It also has power steering and brakes and the Plymouth Road Runner horn, which makes a "Beep! Beep!" sound like the cartoon the car is named after.

Then there's the 1970 Plymouth Duster in the collection with arguably the best paint scheme. It's bright green with groovy "DUSTER" lettering on the hood and various contrasting panels. It's actually the second scheme the car used, as according to Mecum, the car was built for the 1970 tour and then redesigned for the 1971 tour. The paint is matched with color-coordinated wheels and blue and green floral pattern floor mats. There are unique body changes, too, such as the custom headlight housings, functional brake air ducts up front, fake extractor vents above the rear window, racing-style fuel cap and rectangular exhaust. Mechanically, it has a stock 275-horsepower 340-cubic inch V8 and four-speed manual transmission.

While it doesn't sport as lurid a paint scheme, the older 1970 Plymouth Road Runner is still bold, and has more body styling changes than the Duster. Up front it features a custom grille and rectangular headlights. Along the side, the door handles have been removed, and fat four-inch fender flares fitted. The tail has a molded-in rear wing and unique one-piece taillight lens. The car's paint is a triple-tone of black, white and an orange gold that reflect the colors in the cartoon Road Runner's dust trail. The character is featured prominently on the doors with its trail extending into the side scoops. The paint scheme is reflected inside with custom floor mats. Under the hood is a stock 425-horsepower 426-cubic inch Hemi V8 backed by an automatic transmission.

The last of these concepts wasn't actually a Plymouth Rapid Transit System car, but it was built in a similar style, and it made its debut at the 1969 Chicago Auto Show. It's a 1969 Dodge Dart Swinger, and its exterior modifications include rectangular headlights and close-set grille-mounted fog lights. It has what looks like a big intake poking through the hood, but it's actually a dummy with no mechanical linkages or even a duct to the intake underneath. The sides have been streamlined with the door handles hidden behind the door edges. At the back, a subtle spoiler has been molded into the body, and single-piece taillight lenses have been added. The interior is stock as is the 340-cubic inch V8, 4-speed manual and power steering and brakes.

All of these cars can be seen at the Mecum Indianapolis auction May 14-19. And if you have some serious cash, you might even be able to bring one or all of these home with you.