South Australia Vehicle Modification Guide
Engineering, certification and DIT/NHVR approval pathways for modified vehicles in South Australia.
KME Vehicle Engineering helps vehicle owners, workshops and businesses understand the engineering and approval pathway for light and heavy vehicle modifications in South Australia.
Reviewed by Daly Kelly — KME Vehicle Engineering
Last reviewed: September 2026
Modifying a vehicle in South Australia
Vehicle modifications in South Australia are regulated through the Department for Infrastructure and Transport (DIT) and, for certain heavy vehicle modifications, the National Heavy Vehicle Regulator (NHVR).
​
Depending on the vehicle and proposed changes, the process may involve prior approval, engineering assessment, inspection and documentation before the modified vehicle can be accepted for road use.
1. Determine the pathway
Identify the vehicle category, proposed modifications and applicable requirements. For significant light vehicle modifications, DIT may issue a Statement of Requirements before work begins.
2. Complete the engineering
Undertake the required design assessment, calculations, modification work, inspections and testing. Where specified, obtain a report from an appropriately recognised engineering signatory.
3. Complete the SA approval process
Submit the required engineering evidence, complete any necessary vehicle inspections and obtain the applicable DIT approval or heavy vehicle certification documentation. Update registration details where required.
South Australia's Department for Infrastructure and Transport (DIT) considers engineering reports from interstate engineering signatories recognised by their respective jurisdictions.
Daly Kelly is an NT Recognised Signatory and a QLD Approved Person, so KME Vehicle Engineering can assist customers under this interstate pathway.
Who approves vehicle modifications in SA?
The South Australian Department for Infrastructure and Transport (DIT), through Vehicle Standards, administers the state's light vehicle modification approval process.
For modifications requiring formal assessment, DIT may specify engineering evidence, inspection requirements and conditions that must be satisfied before approval.
South Australia uses a Light Vehicle Engineering Signatory (LVES) system for engineering assessments of relevant light vehicle modifications.
For heavy vehicles, the National Heavy Vehicle Regulator (NHVR) administers aspects of the modification approval framework, while DIT operates a Recognised Engineering Signatory (RES) scheme for relevant heavy vehicle modifications.
An engineering report supports the approval process but does not, by itself, guarantee acceptance by the relevant authority.
Light vehicle modifications in South Australia
Vehicles up to 4.5 tonnes GVM
Light vehicle modifications in South Australia are assessed against applicable Australian Design Rules (ADRs), South Australian vehicle standards and relevant national technical guidance, including VSB 14 where applicable.
The approval requirements depend on the vehicle and the nature of the modification.
-
Minor modifications may be permitted without a formal engineering report, provided applicable requirements are met.
-
Significant modifications may require an application to DIT before work begins.
-
DIT may issue a Statement of Requirements identifying engineering and inspection obligations.
-
An engineering report from a recognised LVES may be required.
-
A Certificate of Exemption and roadworthy inspection may be required for certain modifications.
Common modifications requiring further assessment can include engine conversions, significant suspension lifts, chassis alterations, steering modifications, seating changes and GVM upgrades.
Owners should confirm the approval pathway before purchasing components or commencing significant modification work.
​
Heavy vehicle modifications in South Australia
Trucks, buses and specialist vehicles
Heavy vehicle modifications in South Australia operate within the Heavy Vehicle National Law framework, supported by the NHVR Code of Practice for the Approval of Heavy Vehicle Modifications and applicable technical standards, including VSB 6.
The required approval pathway depends on whether the modification falls within an established code of practice.
-
Modifications within the applicable code may require assessment and certification through a DIT Recognised Engineering Signatory.
-
Modifications outside the relevant code may require specific NHVR approval before work begins.
-
Engineering evidence may include design calculations, component specifications, inspection records and test results.
-
DIT approval and applicable vehicle inspection or registration requirements must also be addressed.
Common projects include GVM and GCM upgrades, axle and suspension modifications, chassis alterations, body conversions, wheel and tyre changes, and specialist heavy vehicle modifications.
​
GVM upgrades in South Australia
A Gross Vehicle Mass (GVM) upgrade increases the maximum permitted mass of a vehicle, subject to the applicable technical and regulatory approval process.
For vehicles already registered in South Australia, the proposed upgrade must be assessed against the relevant post-registration modification requirements.
Engineering considerations can include:
-
Manufacturer specifications and original vehicle ratings
-
Axle and suspension capacities
-
Braking performance
-
Wheel and tyre load ratings
-
Vehicle stability and handling
-
Compatibility with existing modifications
-
Supporting test and engineering evidence
The approval process differs depending on whether the vehicle is classified as light or heavy, and whether the upgrade occurs before or after first registration.
A GVM upgrade does not automatically increase Gross Combination Mass (GCM) or braked towing capacity. These ratings require separate consideration.
Frequently asked questions
Official SA resources
-
Apply to modify a light motor vehicle
-
Vehicle modification requirements for cars
-
Heavy vehicle modifications
-
Light vehicle seating alterations