
Lightning McQueen in Eddie's bodyshop
The task to transform cartons into real cars was given by Pixar to Eddie Paul's "Customs By Eddie Paul", a division of EP Industries, Inc.
The project included real-life versions of the characters "Lightning McQueen" (based on a Pontiac Trans Am), "Sally Carrera" (based on a Porsche 911) and tow truck "Mater".
Each vehicle was built in less than one month; the development process included computer 3D modeling - done in Rhino - CNC machining and the bodyshop expertise of Eddie's team.
The cars were displayed at various automotive events to promote the movie and were presented recently at the SEMA Show.
Among the technical difficulties of this particular jobs was the presence of mouths in place of the front grilles. In order to get airflow into the engine, Paul's team installed intake fans to collect air from the underbody and the interior.
The original article on cadalyst goes through some interesting details of the development process.
A complete list and image gallery of the vehicles featured in Pixar's Cars can be found on Top Gear.

Eddie Paul and "Mater" in real version
Customs By Eddie Paul is the automotive division of E.P. Industries, Inc. specializing in custom cars, rods, trucks and motorcycles. They also create stunt vehicles, show vehicles, props and special effects under extreme deadlines for all of Hollywood’s major film and television studios. Their special vehicles were featured in many movies, including:
In addition to the studio and automotive work, Customs By Eddie Paul produces a series of How-To DVDs and videos geared for the do-it-yourself automotive enthusiast and mechanic.
E.P. Industries specializes in the design, development, prototyping and manufacture of many non-automotive technologies for the government, fire-fighting, U.S. Military, and aerospace industries. In addition to our complete automotive capabilities, our 25,000 sq. ft. facility includes 15 CNC work stations, CNC router, CNC plasma-cutting, 3-D digitizing, metal fabrication and welding shop, plastics and woodworking, vacuum-forming, and state-of-the-art digital animation, digital photography, video production and editing.
(Source: cadalyst, EP Indutries, Inc.)