Steinwinter Supercargo 20.40: The Futuristic Tractor-Trailer Built Like a Supercar

Manfred Steinwinter was one such dreamer, though we could argue that his biggest innovation, which is also the one thing that he's best remembered by, did not so much help the automotive industry make any progress. But part of being a dreamer is the very real possibility of failure, so for every dreamer innovator, there are at least a handful who have dreamed and failed.

Manfred Steinwinter is one of them, thanks to the Steinwinter Supercargo 20.40 tractor-trailer concept. The concept held enough promise to warrant backing from Mercedes-Benz, generate interest with DAF and Isuzu, and lead to the building of a fully-functional prototype that saw some road testing and spurred talk of the future of the cargo-hauling industry. None of it was enough to take it into the next stage before real-world testing and planned legislation drove the final nail in the coffin. RIP, beautiful dream.

If you're game for one more cliché, they say you shouldn't try to reinvent the wheel. Not that this has ever stopped anyone from trying, and if you think about it, we've seen some very awesome, if not exactly practical successful examples of reinvented wheels. The Steinwinter Supercargo wanted to be just that but to the trucking industry, with Manfred Steinwinter convinced that a lower profile for the tractor-trailer would result in better aerodynamics through reduced drag, lower consumption, and, best of all, more space for cargo hauling.

The 20.40 concept was revolutionary in every way that counted, promising a modular trailer that could be used in a variety of scenarios, that could double as a daily driver with excellent maneuverability around the city, increased fuel efficiency, more comfort, and more room to transport goods.

It was that last promise that got the attention of Mercedes-Benz, who became a partner in the project, with the Stuttgart-based smaller company fronted by Steinwinter. The 20.40 concept would allow for a maximum length of 18 meters (59 feet), which would result in 150 cubic meters (5,297 cubic feet) for cargo transport and about one-third more space up top to haul whatever needed hauling.

"Up top" is not a typo, as you've already inferred from the photos attached to this story. The innovation proposed by the Steinwinter Supercargo 20.40 was the fact that it was a cab-under, so it drove from under the trailer. It was 2.5 meters (8.2 feet) wide and just under 1.2 meters (3.9 feet) high (1,170 mm/46 inches, to be more precise), so it sat as low to the ground as a supercar.

The cabin was styled like in a supercar, too, though it didn't lack some of the comforts of a proper tractor-trailer. The driver and two other passengers would sit in leather Recaro bucket seats, or the third seat could be switched for a small cot. There was a matching dashboard and leather finishes, but also a hidden cupboard and an integrated closet, making for a much homier cabin on long trips.

More impressively, the vehicle had features innovative for the time, like adjustable air suspension, ABS, climate control, and a limited-slip differential. Due to its low height, it could be driven in the city like a regular car, which extended its potential functionality. It could get a variety of powertrains and would work on a variety of trailers, with Steinwinter imagining it as suitable for anything from luxury coaches to buses, RVs, toy haulers, and even mobile infirmaries. He never got beyond dreaming about these possible uses other than to commission some printed ads with drawings; to our knowledge, only one Supercargo was built, though variations and modifications were added to it during testing.

That unit was presented to the public at the 1983 Frankfurt Motor Show, where it was met very warmly both by industry peers and the media. Since it had backing from Mercedes-Benz, who had donated the chassis for the prototype, it immediately generated interest from competitors, though it would never amount to anything concrete.

The tractor featured a Mercedes-Benz OM442 400-hp engine mated to a 16-speed ZF transmission. It was definitely good enough to tow the extended trailer, but the low height allowed for improper cooling of the engine, which led to serious overheating issues during subsequent road tests.

Other issues also became apparent, particularly heavy understeer and poor visibility, so drivers hated the experience. The final blow came with the announcement that, as of 1990, European legislation would cap off the total length of a truck to 18.75 meters (61.5 feet), of which the usable loading area would be no longer than 15.65 meters (51.3 feet) – where the Steinwinter Supercargo promised 18 full meters (59 feet).

The Steinwinter Supercargo project was killed off after just 3,000 km (1,864 miles), and the prototype has been lost to time since. In 1987, the concept made a soft comeback with the premiere of the (short-lived) doomsday NBC series The Highwayman with Sam J. Jones, which featured a few trucks directly inspired by the original design.

One of them was included in the opening credits, as you can see in the video below, if you can take such a huge dose of pure '80s fabulousness. It was actually a modified Peterbilt and lived an active life as a show truck for years after the show's cancelation. It reemerged online in 2022, asking $65,000 and looking as if it had just survived the second coming of the end of days.

As for the original 1983 Steinwinter Supercargo 20.40, there is no evidence of it ever being captured on video in motion.