If you happen to be in Ingolstadt, Germany between February 1st and the end of April, then you have the opportunity to see 40 years worth of Audi concept cars on display at the company's Forum Ingolstadt museum.
Some of these jaw-dropping concepts are legendary, including the Avus Quattro (shown) that, according to Inside Line, marked the first appearance of a W12 engine in a VW product. The group of concepts includes everything from a 1976 Audi motorcycle to the RSQ, the company's resident movie star that appeared in the film (and I use that term loosely) I, Robot alongside Will Smith.
Audi's in a small class of manufacturers that tends to create concept cars that have a viable chance of being produced (think Chryser). The Le Mans Quattro concept is a recent example, as the production version, called the R8, will soon go on sale with a version of the Lamborghini Gallardo’s V10 powerplant.
If you can’t make it to Ingolstadt, check out this page on ConceptCarz to see pics and specs of Audi’s concepts going back to 1968.