It still looks incredible to this day.
Today, the cars we see in NASCAR have so little in common with the cars which they are said to be based off of that you'd be forgiven for wonder why they bother to make these claims at all. It wasn't always like this, and there was once a time when stock car race actually involved cars that were showroom stock. That meant homologation, and the undisputed all-time great icon of NASCAR homologation is the Plymouth Superbird. Strictly speaking, the Superbird was not Chrysler's first "aero" car.
In 1969, Dodge raced with a modified version of the Charger, called the Charger 500. This was the first American car to be designed in a wind tunnel, but it didn't last long. It was further modified with the addition of the nose and spoiler before the end of the season, thus becoming the Charger Daytona. The Daytona was massive success on the track, but Plymouth had the idea that they could do even better. The lessons learned from the Daytona went into the building of the Superbird in 1970, which became the even more successful and iconic version of the car.
The Daytona was essentially an options package for the Charger, and a number of existing Chargers were retrofitted to become Daytonas. There were a few problems with this. Since the Daytona wasn't designed to have the nose on the front, which diverted air around the radiator, rather than through it, the Daytona suffered from overheating problems at low speeds. Although the Superbird was technically a modified Road Runner, it was treated more like a separate model than an options package, and the differences between it and the standard car were much more extensive than they had been with the Daytona.
Racing versions of the Superbird used Chrysler's legendary 426 Hemi V8, a highly advanced (although extremely expensive) advanced engine at time, which produced 425 horsepower. This engine was offered for the street version of the car, along with the 440 Super Commando and 440 Super Commando Six Pack, although the high price of the 426 Hemi models mean that they are the rarest of the Superbirds. Powerful engines and good aerodynamics meant that the cars were fast (the street version of the car could hit 160mph) especially for 1970. Production numbers are better than those of the other cars on this list.
In 1969, NASCAR homologation rules stated that 500 copies of a car had to be built, but there was a rule change for the 1970 season in which the Superbird would compete. The new rule stated that each manufacturer would have to build two cars for each dealership they had in the US. The rule was a bit weird, but it was fair, and it meant that Plymouth now had to build 1,920 Superbirds. This is good news for collectors, since about 2,000 ended up being built, and if it weren't for the rule change, they would probably be as rare as the Lancia Stratos. Of course, they are still quite rare, and the Hemi cars in particular command high prices today.
The look of the Superbird is, admittedly, a bit weird. It's a look which definitely grows on you, and you might even (as I have) grow to love it. But in 1970, before people had a chance to get used it, it just looked weird. This look, and the steep price, meant that many Plymouth dealerships ended up with Superbirds sitting unsold on their lots for many months. Part of the problem was that aerodynamics weren't a particularly sexy feature for cars to have at the time. This was the height of the muscle car era, and big, powerful engines were what consumers wanted. After all, as Enzo Ferrari had once put it "aerodynamics are for people who can't build engines".
Of course, on the track, the aerodynamics of the car allowed it to reach speeds of up to 200mph, but on the street, they were mostly just extra weight. There is some disagreement over the reasoning behind the rather extreme height of the Superbird's spoiler. A few decades after the car first appeared, a former Chrysler engineer was quoted as saying that there was nothing special about the height, and that it was designed simply to be tall enough for the trunk lid to open. But this was only one saying it, and it was never officially confirmed, so many still believe the older story that the height was determined as the result of careful and extensive testing.
Plymouth did manage to have some fun with the car. The typically outrageous Chrysler paint colors of the time were offered for it. It got special decals on the spoiler struts depicting the Road Runner of cartoon fame holding a racing helmet, and the horn even mimicked the cartoon character. These are uncharacteristically whimsical touches for a homologation car, but not everyone feels the need to take themselves as seriously as Ferrari. With both NASCAR homologation and Plymouth now gone, it seems that the 1970 Superbird will remain the only model year of the iconic nameplate.
However, there have been a few aftermarket companies who have taken a stab at creating a new Superbird out of the new Challenger. These are pricey, but if you absolutely must have a Superbird, it's still cheaper than an original.