The past year has seen concepts lighting up car shows from LA to Tokyo, which has made this the hardest of our looking-back series to compile. Consider that we were forced to eliminate the following concepts from the top 5, and you'll appreciate the difficulty we had. Those that missed the cut include the S-Class Concept Coupe, Opel Monza, Jaguar C-X17, Volvo Concept Coupe, Audi Sport Quattro, and Aston Martin CC100 Concept. But that can only mean the five that did make it are very special indeed.

Honoring Pininfarina's late chairman, the Sergio is based on the Ferrari 458 Italia but remade as an extreme roadster. Its Barchetta bodystyle takes a similar form to the Lamborghini Aventador J and Aston Martin's CC100 with no roof or windshield whatsoever – just an open cockpit with an integrated roll bar and a pair of crash helmets. With the 4.8-liter Ferrari V8 channeling 570 horsepower to the rear wheels, the Sergio is quoted at a 3.4-second 0-62 time and a 199 mph top speed.

Picking up the mantel from the gorgeous Ciel concept, the Cadillac Elmiraj explores new areas of the marque's Art & Science philosophy. The four-seater coupe is powered by an all-new 500-hp 4.5-liter twin-turbo V8 and boasts signature Caddy design cues including a long dash-to-axle front profile, vertical front and rear lamps, while its performance credentials are evidenced by two vents in the long hood, 22-inch alloys housing large ceramic brakes and monoblock calipers. The rich blue exterior finish wears the Vsport badge and a new wreathless Cadillac Crest marking a new era of design.

An evolution of the Giugiaro Parcour Concept unveiled at Geneva, the Audi Nanuk Quattro Concept, is powered by a newly-developed 5.0-liter twin-turbo V10 diesel unit rated at 544 hp and 738 lb-ft of torque, which is sent to all four of its 22-inch wheels via a seven-speed S tronic and a specially-designed AWD Quattro system. The 1,900 kg two-seater sprints from 0-62 mph in 3.8 seconds and manages a top speed of 190 mph. Audi fitted the concept with its latest adaptive air suspension that allows the driver to drop the car 30 mm closer to the tarmac or raise it by 40 mm. The system also automatically controls the level of the body using the sat-nav and driving speed for guidance.

Built on the chassis of a C6-gen Corvette, the Laraki Epitome Concept weighs just 2,800 pounds thanks to body panels made entirely of carbon fiber. Power comes from a 7.0-liter Chevy V8 twin-turbocharged to create 1,200 hp on regular gas. There's an additional gas tank for 110 octane and with a touch of a button, gas can be burned from both for an output of 1,750 hp. That figure is almost as unbelievable as the $2 million price tag. Laraki is planning a nine-unit limited production run of its supercar.

Taking its name from the Italian word for selfish" due to its single-seat cockpit, the Egoista adopts Lamborghini design traits, but looks like the result of a LSD-fueled threesome involving a Veneno, KTM X-Bow and Batman Tumbler. Lamborghini says the cockpit's design was inspired by that of an Apache attack helicopter, while in place of the familiar scissor doors, there's a jet-style canopy and the driver needs to remove the steering wheel in order to exit (like in a formula racing car). Power comes from the Gallardo's 5.2-liter V10 tuned to 600 horsepower.