The Amelia Island Concours d'Elégance is a serious car show in the sense that it's run in a highly professional manner and features high-caliber cars and judges, but not in the sense that it takes itself more seriously than any car show should.

Proof of the latter was the "What Were They Thinking" class of automotive oddities at this year's event, which happened over the weekend. Our friend Rob Sass, Publisher of Hagerty Classic Cars Magazine, was at the show and submits these five as his favorites:

1974 Fascination (above)

Looking like a prop from a bad sci-fi movie or a "cars of the future" illustration from a 1930s issue of Popular Mechanics, eccentric would-be auto tycoon Paul M. Lewis originally envisioned the car to be propeller-powered. Eventually, he abandoned the idea of a pedestrian Cuisinart and settled on this Renaut-powered creation. Five of these oddities were build in Sidney, Nebraska before Lewis' obviously saner board members ousted him and put an end to the madness. All five cars survive today in the hands of just two collectors.

Rob Sass is the Publisher of Hagerty Classic Cars magazine. He is a regular contributor to the automotive section of the New York Times and is the author of "Ran When Parked, Advice and Adventures from the Affordable Underbelly of Car Collecting."

1962 El Tiburon Roadster

Enzo Ferrari once said that "aerodynamics are for people who can't design engines." Had he seen the El Tiburon, he might have asserted that aerodynamics are for people who simply can't design anything. Known as "the Shark," it was the product of an obsessive-compulsive drive to produce as low a coefficient of drag as possible. Road & Track magazine recognized it as the slipperiest car extant in 1966. Little was heard of it after this.

1959 F.M.R. TG 500 Tigre

Based on a design by Messerschmitt, aircraft purveyor to the Third Reich, the Tigre was a bid to create a new category of micro muscle cars. Boasting a sizzling 24 horsepower, it could provide performance on par with a VW Beetle 1300 with a dead cylinder. One recently sold at an auction of microcars for over $300,000, making it perhaps the most expensive car ever on a price-per-pound basis.

1963 "Shorty" Mustang prototype

A pre-production prototype build for Ford to gauge the possibility of producing a smaller two-seater Mustang, it presaged the AMC AMX (a shortened AMC Javelin). And while the AMC actually looked pretty good from most angles, the shorty Mustang simply looked ridiculous – all overhang and no wheelbase. The designer actually "kidnapped" the car when he thought Ford was going to crush it and walled it up in a warehouse until he realized that his noble act actually constituted a crime.

1957 Spohn Convertible

The world is no stranger to homely cars from the Edsel to the Pontiac Aztek. However, these cars are rank amateurs in the aesthetically challenged field when compared to the 1957 Spohn Convertible. Less a car than simply a collection of unharmonious, styling clichés, it was said to have been custom-built by the West German coachbuilder Spohn to the Mad King Ludwig-esque desires of its first owner.