Melbourne, Sydney and Brisbane will be hardest hit by petrol shortages while more than 100 of Cootes Transport tankers are grounded or forced to undergo repairs.
Melbourne fuel supplies will be under the most stress, as Cootes has its largest hub in Victoria, followed by parts of Queensland - particularly Brisbane - as well as Sydney and Adelaide.
Australasian Convenience and Petroleum Marketers Association (ACAPMA) chief executive Nic Moulis said Cootes' hub worked mainly in metropolitan areas and shortages were already starting to pinch.
"It is reasonably widespread through metropolitan areas," Mr Moulis said.
"Definitely Melbourne will be the worst.
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"Queensland will be second, Sydney won't be as bad as Queensland."
Mr Moulis says regional areas will escape the disruption relatively unscathed.
The company, which could face prosecution if VicRoads finds it breached the Road Safety Act, is being investigated following a tanker crash that killed two people in Sydney last week.
Authorities grounded 79 Cootes trucks in Victoria and 23 in NSW.
Service stations are urging the public not to panic buy petrol.
Shell is increasing fuel deliveries to service stations across Australia, but said only Victoria, Adelaide and southeast Queensland will be affected.
They expect capacity to be restored by the end of the week.
A BP spokesman said service stations in Melbourne, Sydney and Brisbane were experiencing the greatest shortage of tankers, with Melbourne being hardest hit.
Some stations were short one or more grades of fuel while there were others "that don't have anything", he said.
He urged motorists to be patient as BP works to get product back into its stations.
Mr Moulis said while it was a concern so many trucks were taken off the road, the industry would act quickly to ensure sites continued to be refuelled.
"As sites start to run out and become critical they will be prioritised on a scale and we will move to make sure those sites are refuelled," Mr Moulis said.
VicRoads is now reviewing Coote's heavy vehicle accreditation.
NSW's transport agency said it didn't expect bus services to be disrupted by the fuel shortages across the state.
"Since last week, we have been working with our fuel supplier and are confident delivery schedules will meet our needs," a Transport for NSW spokesman said in a statement.
