Pressure on as fuel prices rise three times more quickly than incomes or inflation.
Families are going without fresh fruit and vegetables to pay for petrol which has increased in price three times faster than household incomes.
With petrol prices at near-record levels the Automobile Association (AA) has warned motorists to expect 91 octane prices to top peak of $2.22 a litre, reached last May. .
AA PetrolWatch spokesman Mark Stockdale said pump prices had not changed over the past month because of stable commodity prices.
"Despite that, it is near the record price that we have ever paid. And this is in spite of those stable commodity prices.
"What would we be paying if the commodity price was volatile, or if our exchange rate was not at near record highs?"
AA records show prices of 91 octane rose 45 per cent from $1.52 a litre in mid-April 2007 to $2.20 a litre today.
Household incomes increased by about 15 per cent over the same period.
The Family Budgeting Services Federation and Citizens Advice Bureaux say an increasing number of people are going without healthy food to meet essential costs such as petrol.
Family Budgeting head Raewyn Fox said lower-income families were often reliant on their cars, which were often older and less fuel efficient, "to get to work at funny shift hours across town where transport routes don't go. And particularly families where mum's got little kids, and she's trying to go back to work.
"Since the recession incomes haven't gone up considerably. That's one of the biggest factors. And a lot of people have virtually had no pay increases, even to cope with inflation."
When budgets were squeezed, items such as fresh fruit and vegetables were often first to go, she said.
"That's usually one of the only discretionary things. Your rent is set, you have to pay your power bills, your phone bills - the only thing that can be changed is food."
Yesterday, Green Party co-leader Dr Russel Norman attacked the Government's transport policy as being blind to the reality of increasing petrol prices.
"Petrol is rising three times faster than incomes or general inflation. This is having a chilling effect on our economy," he said.
"The Government will spend $14 billion over the next 10 years on their flagship Roads of National Significance programme.
"This programme will only make our economy more reliant on petrol ... we can break our reliance on petrol by investing in smarter alternatives to roads."
But Mr Stockdale said while alternatives to roads needed to be developed, the reality was most transport was by motor vehicle.
"Even under future oil price scenarios, that is not expected to change substantially ... what will change is that vehicles will become more fuel efficient."
He said fuel cost would then be offset by fuel efficiency.By Nicholas Jones Email Nicholas