Another example is the Utah Salt Flats Racing Association which is concerned solely with the speed of a vehicle. The Association uses its own definition of a production vehicle. The Association allows quite a high level of modification over the original. In 2006 a Pontiac TransAm of John Rains Racing was classified as being the fastest production model (Bonneville D/PS class) with a top speed in excess of 297 mph. Road tests of the same type of car available from the production line were incapable of anything like this speed and "Popular Mechanics" referred to the car as "production based", which was probably a more accurate description.