Improved Production, formerly known as 3J Club Cars, is the fastest growing category of circuit racing in Australia. It is classified by CAMS as category 3J.

An Improved Production car is loosely based on a modified road car, and is made popular by the fact that it is fast and relatively inexpensive, as far as race cars go. Starting out with a production body shell, and then carrying out substantial modifications to engines, brakes and suspension, has proven popular both with beginners to the sport and more experienced competitors. You are allowed to fit a bigger engine from the same manufacturer as the body shell.  It can be a twin cam, or a turbo (with a restrictor), or a bridge or peripheral port in the case of a Mazda, depending on the model.

You can lower the car to within 100mm of the ground, excluding the exhaust, and can change springs, shocks, sway bars and fit urethane bushes. Wheel width can be increased to 7inches for a car over 3 Litres in capacity. Brakes can be anything you like but must be dual circuit, you can use close ratio gear boxes with a maximum of five forward gears, and locker or limited slip diffs are allowed. You are allowed to fit flares, and front and rear spoilers of limited sizes.

Improved Production race cars also use a control tyre which is the Yokohama A048R. The variety of cars and the low cost make it a very accessible category, ideal for drivers starting their racing career.