In its November budget, the state government said it would introduce the charge, expected to initially raise about $1 million a year, in July this year.

But it will now come into force in July 2022.

Victoria is also planning similar legislation, to come into force in July this year, while the NSW treasurer is expected to take a proposal to state cabinet later this year.

Treasurer Rob Lucas said SA's legislation would be based on a similar distance-travelled scheme as Victoria, with motorists providing odometer readings to ensure all road users contributed fairly to the state's road maintenance investment.

"The reality is, if you're driving an electric vehicle then you're not paying fuel excise at the pump and you're contributing significantly less to the vital upkeep of our vast road network," Mr Lucas said.

"Ultimately this reform will have to happen.

"As more and more Australian motorists shift to zero and low-emission vehicles, all governments will need to ensure there is sufficient funding for ongoing road maintenance and infrastructure investment."

Under Victoria's model, charges will apply to light vehicles not predominantly powered by a fuel source subject to commonwealth government fuel excise, such as petrol, diesel or LPG.

A 2.5 cent/km charge would apply to electric and other zero-emission vehicles and hydrogen vehicles, and a 2.0 cent/km charge would apply to plug-in hybrid electric vehicles.

Mr Lucas said SA's decision to delay the measure would also allow more time for industry consultation.

Australian Associated Press