Audi Quattro
In the early 1990s, Audi developed a concept car known as the Audi Quattro Spyder. A clear throwback to the successful rally road car of the early 1980s, which was simply called the Audi Quattro, this new concept proved to be a success when first shown at the 1991 Frankfurt Motor Show. Enthusiasts began to call for a production version, provoking Audi engineers and accountants into discussion of whether or not there was a viable business case for such a vehicle. Ultimately, Audi decided against a production version.