The price of petrol has hit an eight-month high, chiefly because of higher crude oil prices.
Fresh data from the Australian Institute of Petroleum shows the average price of unleaded petrol rose 1.5 cents a litre over the past week.
The national average is now $1.22 a litre.
CommSec economist Savanth Sebastian warned there was worse to come for motorists.
"The Singapore oil price has jumped by almost 40 per cent in the space of the last month but is yet to be reflected fully in domestic pump prices,'' Mr Sebastian wrote in a market update.
He said the predicted continued rise of the Australian dollar would not insulate motorists.
"The last time oil was trading above $100 a barrel, pump prices were holding over $1.35 a litre.
"CommSec expects pump prices to jump by a further five cents a litre in the next fortnight.''
