In Australia, each state has its own standards for issuing registrations for vehicles; the roadworthy inspections that are done for vehicles will then also vary by state. While each state will generally require a check on features of the vehicle that affect its overall safety, such as brakes and steering, note a few additional factors about roadworthy inspections in South Australia, and what vehicles may be required to get these inspections, regardless of the car's age or overall condition.
The overall construction has changed
If you've had the top removed from your sedan so it's now a convertible, or installed a lift kit so that the vehicle is higher than before, you will probably need a roadworthy inspection on that vehicle. This also applies to changes made inside the vehicle, if the seating capacity is now different. There are regulations that affect the seatbelts required in a vehicle, and any change in the seating may mean that the vehicle needs to be inspected to ensure it has all legally required seatbelts. If you're not sure if the changes made to the frame or structure of the vehicle would require a new inspection, be sure to ask your mechanic, or check with your state licensing office before you apply for a new registration, so you can schedule that inspection as needed.
Has been fitted with nonstandard or rebuilt parts
If your car has been fitted with a nonstandard engine, you will need to get the car inspected, to ensure the engine is powerful enough to maintain certain speeds on the road, and to ensure the car can manage the power the engine offers when it comes to braking, steering, and so on. Certain rebuilt parts may also need an inspection, to ensure they're safe and won't cause any hazards on the road.
If you're not sure which rebuilt parts would require an inspection for your vehicle, check with your smash shop, as they should know if any parts they use would mean the vehicle will need a new inspection. If you made repairs yourself using rebuilt parts, check with your state licensing office.
If your vehicle has been issued a major defect notice, it may need a roadworthy inspection even after that defect has been repaired. The notice you receive about the defect may tell you if you'll need to get this inspection after work is done, so be sure to keep that notice and read it carefully, so you know your requirements before putting the vehicle back on the road.