In the 1970s, Michelin developed a highly specialized vehicle known as the PLR, or "Centipede," to safely test truck tires at sustained high speeds. Built on a heavily modified Citroen DS chassis, this ten-wheeled mobile laboratory utilized a unique hydropneumatic suspension to maintain stability and simulate heavy cargo loads. The massive vehicle featured dual Chevrolet V8 engines, with one dedicated to driving the car and the other powering a hidden eleventh wheel used for testing in the center of the chassis. This internal configuration protected the driver from catastrophic tire failures while allowing engineers to gather precise data in real-world conditions. Although modern indoor technology eventually rendered the project obsolete, the Michelin PLR remains a legendary piece of automotive history currently preserved in a French museum.

The Karlmann King is a high-end, custom-built vehicle recognized as the most expensive SUV in the world, with prices reaching up to $3.8 million. Constructed on a Ford F-550 chassis, this massive machine features a sharp, angular exterior inspired by stealth bombers and diamond shapes. While its 6.8L V10 engine provides significant power, the vehicle's extreme weight—which can reach 6,000 kg with optional bullet-proof armor—limits its top speed to only 87 mph. The interior is designed for ultimate luxury, offering amenities such as a coffee machine, 4K television, gaming console, and satellite communication. Produced in very limited quantities in Italy and the United States, each unit is a bespoke creation tailored to the extravagant tastes of its owners.

The TVR Cerbera Speed 12 was an ultra-high performance concept car from the late 1990s, initially designed for GT1 racing to challenge the McLaren F1. It featured an extreme 7.7-liter V12 engine, which was so potent it reportedly broke the dynamometer during testing, with power estimates nearing 1,000 horsepower. Weighing just over 2,200 pounds, it was projected to hit 60 mph in 2.9 seconds with a top speed over 240 mph. Ultimately, TVR's owner, Peter Wheeler, canceled the planned production, declaring the single finished prototype too savage and unusable for public roads. Only one road-legal example exists.

The Italdesign Aztec, designed by Giorgetto Giugiaro and unveiled in 1988, is a rare, low-slung sports car known for its futuristic, "Blade Runner" style. It is unique due to its dual-canopy speedster body, which completely separates the driver and passenger into individual cockpits, requiring electronic communication. The car uses an Audi-sourced turbocharged 2.2-liter five-cylinder engine routed through a five-speed manual gearbox and a four-wheel-drive system. Incorporating features inspired by space technology, the Aztec was produced in extremely limited numbers, with only about 18 examples reportedly built.

The Maserati Boomerang is a one-off concept car designed by Giorgetto Giugiaro for Italdesign, debuting as a running model in 1972. Built on the Maserati Bora chassis, it featured a 310 hp, 4.7-liter V8 engine, capable of nearly 300 km/h. Its extreme, angular wedge shape and futuristic interior—where the steering wheel rotated around the stationary gauge cluster—were revolutionary. Though never produced, its styling proved highly influential, inspiring later designs like the VW Golf Mk1, Lotus Esprit, and the DeLorean.

The Tatra 603 was a large, luxurious, rear-engined sedan produced by the Czechoslovak company Tatra from 1956 to 1975. Designed secretly by engineers when the company was ordered to only build trucks, it quickly became the vehicle of choice for high-ranking Communist party and industry officials. It featured a streamlined, all-steel body and a unique air-cooled 2.5-liter V8 engine mounted behind the rear wheels. The six-passenger car was rarely available to the public and came initially with a distinctive three-headlamp arrangement.

The 1962 Ford Seattle-ite XXI, designed by Alex Tremulis for the Seattle World’s Fair, was a highly visionary concept car. It featured a unique six-wheel layout, with four steerable front wheels, intended to enhance tracking and braking efficiency. The vehicle’s modular design allowed the front power capsule to be easily interchangeable, accommodating projected power sources like fuel cells or compact nuclear devices. Advanced interior concepts included fingertip steering and a travel programming computer with a central viewing screen that displayed an automatically rolling road map and estimated arrival time, anticipating modern GPS and digital dashboards.

The CitiCar was a small, wedge-shaped electric runabout produced by Sebring-Vanguard starting in 1974, designed largely in response to the 1973 Oil Crisis. This battery-powered two-passenger vehicle was highly basic, constructed with a tubular aluminum frame and an ABS plastic body. Early models featured limited performance, typically offering top speeds under 40 mph and a range of about 40 miles, suitable for local commuting. Including its successor, the Comuta-Car, approximately 4,400 units were sold. The CitiCar held the title of the best-selling electric car in the United States after WWII until 2011.