A rise in wholesale petrol prices means drivers could be feeling the pinch at the bowser as school holidays begin.
With school holidays having already started in Melbourne - and the AFL Grand Final approaching - CommSec analysts suggested Melburnians leave the car at home, with prices averaging $1.64 a litre today.
The latest report from the Australian Institute of Petroleum shows wholesale unleaded prices climbed 4.6 cents last week.
NRMA's Peter Khoury said this meant retail prices could go up as soon as Friday.
Mr Khoury said even before the attacks on two Saudi Arabian oil processing plants earlier this month, petrol prices were set to rise.
He blamed that on the United States' escalating trade war with China, a weak Australian dollar and oil-producing nations cutting production to up prices.
"Australia has no control over the factors that cause prices to go up," Mr Khoury said.
"We are highly exposed to the volatility of world oil prices."
Commsec said with repairs to the Saudi Arabian oilfields set to take months and increased geopolitical tensions, global oil prices were set to rise further.
The national average retail petrol price rose 0.6 cents last week, a four-month high of 144.2 cents a litre, according to analysts.
The national average retail diesel price rose 0.6 cents to 147.4 cents a litre last week.
Melbourne copped the highest rise in unleaded prices last week, climbing by 15.2 cents a litre.
Brisbane saw the biggest drop in retail petrol prices last week, by 13.7 cents a litre, with prices the second-lowest in the country.
Hobart saw the smallest increase, with 0.1 cents, but the Apple Isle's capital still had the highest average price out of all the other capital cities, at 151.5 cents a litre last week.
The lowest average petrol prices last week were found in Adelaide at 134.5 cents a litre, but this was short lived as the prices hit 157.5 cents a litre on Monday.
Australian Associated Press