It's often a crapshoot when planning an all-new vehicle; who knows whether it'll sell well or not. What looks good on paper and in a design studio may not translate to stellar sales. It happens. Automakers do their best by employing the brightest minds in the necessary fields to try to avoid duds. But every now and then a vehicle starts out life as one thing and then transforms into something else entirely, either by calculated intent or happy accident.

All of the following seven cars have become icons in their respective segments. What makes them special is that they didn't start off in the studio like that. Here's a fascinating look at the early stages of some of our favorite cars.

Lamborghini Diablo

One of our favorite supercars of the 1990s benefitted from a last-minute exterior design change from the original Marcello Gandini design proposal. You see, Lamborghini was not the healthiest car company back then, financially speaking. Before the Diablo was approved for production, the company was sold to Chrysler, and it didn't approve of Gandini's design. Gandini was the brilliant designer who penned the iconic Miura and Countach, but perhaps it was just too radical for a mainstream automaker. The Diablo's final design was ultimately approved in a Detroit, Michigan, design studio. As for the unused design, Gandini later teamed up with a group of ex-Lamborghini employees who started a company called Cizeta. It built a single car: the Cizeta-Moroder V16T, based on Gandini's ditched Diablo design.

Ford Mustang

Amazingly, the Ford Mustang didn't even originally have the now famous Mustang emblem. No, it was a cat. If this sounds vaguely familiar then you're not wrong. While the original Ford Mustang launched in the middle of 1964, early planning prototypes got underway in 1961. Look closely at the pictures shown here and you'll notice that Mustang emblem is not a Mustang but rather a Cougar (or some other large cat). This was soon changed because one of the car's designers was a fan of the World War II P-51 Mustang fighter plane while another Ford executive bred horses as a hobby. The story goes his wife gave him a book titled 'The Mustangs' as a birthday present and, well, the rest is history. As for the cat emblem, that would later be used in 1967 for the Mercury Cougar.

Porsche Panamera

There's no question the Porsche Panamera was a controversial car when it launched in 2010. Porsche has some of the most devoted fans of any car brand in existence and many were dismayed as Porsche launched a second model that wasn't a two-door sports car (the Cayenne SUV arrived for 2003). However, Porsche had been dabbling with building a sedan for quite some time.

As far back as 1988, Porsche designed and built a fairly close to production ready four-door concept called the 989. It featured very 90s styling inside and out, but notice the dark space in between the dashboard's vents; was this an early concept for a navigation screen? Who knows? Although the project was ultimately cancelled in 1992, Porsche never gave up on doing a four-door, non-SUV. It's called Panamera today and not 989.

Mini Cooper

Before BMW ultimately bought the Mini brand from Britain's Rover Group in 2000, a concept was designed and built for a small car that could potentially succeed the iconic Mini, which had been built since 1959. Rover rightly decided a replacement was long overdue, so at the 1997 Geneva Motor Show it revealed a pair of Spiritual concepts, appropriately called the Spiritual and Spiritual Too.

Unlike BMW's first-generation Mini in 2000, these concepts avoided the retro design in favor of something new. Like the original Mini, both were compact, rear-engined, and yet boasted impressive interior space. BMW ditched both concepts entirely when it took over in favor of something not only retro in appearance but also quite premium.

Nissan GT-R

Today's Nissan GT-R comes from a long line of high-performance Nissans (and Datsuns). Before the production-spec GT-R debuted at the 2007 Tokyo Motor Show, Nissan went through a series of design concepts in order to get things exactly right, to best translate the classic Skyline design elements into a modern sports car. As you can see from the included images, there were several proposals, some more aggressive than others.

In the end, it boiled down to three options. Carlos Ghosn, who to this day remains the CEO of the Renault-Nissan alliance, made his final choice based on 1:1 scale models. All three look similar but there are differences. Imagine if he opted for one of the two not chosen. What would that car look like today given its age and styling updates?

Bugatti EB110

Marcello Gandini was a busy guy in the late 80s. Not only did Lamborghini hire him to design the Diablo, but the reborn Bugatti brand asked him to design its first new model in years, the EB110. Just like with the Diablo, Gandini got to work and cooked up an intriguing and, for the time, radical design concept. But it was deemed too radical, even for Bugatti's tastes. The concept you're looking at was ultimately rejected, and Bugatti hired another designer to soften the car's lines. Once again, Gandini was the design visionary, but too often visionaries and bean counters' philosophies collide and those who control the money win the argument.

Bugatti Veyron

Jump ahead a few years to spring 1998 when the Volkswagen Group bought the rights to use the Bugatti nameplate and logo. It quickly got started developing a successor to the EB110 and, as we all know, the Veyron was the final result. But what did the Veyron look like as an early concept? Well, it looked similar but far more curvaceous than the final design. Designed by now-retired VW Group design chief Walter de Silva, this early Veyron concept reminds us an awful lot of today's Alfa Romeo 4C coupe, especially from the top view. It seems to have had more compact dimensions than the production version and a bolder, more striking design.

After ditching de Silva's proposal, Bugatti hired Fabrizio Giugiaro of Italdesign to come up with an alternative. The result was the 18/3 Chiron. Although the name itself wasn't used until 2016, it seems like Bugatti blended elements from both designs for the eventual production Veyron.