The Green Party says petrol could cost $5 per litre in a decade.
On the basis of an International Monetary Fund statement that oil prices could double in the next decade, the Green Party calculated petrol could cost $4.94 by 2022.
Transport spokesperson Julie Anne Genter says the Government also needs to reprioritise its transport budget and spend more on public transport, walking and cycling.
Automobile Association Petrol Watch spokesperson, Mark Stockdale, says $5 per litre is definitely a worst case scenario.
And Transport Minister Gerry Brownlee says the assumptions behind the prediction are questionable.
"Choosing the worst of all of the worlds, which I think this particular calculation does, and then saying that is justification for rewriting the approach to transport infrastructure is very short-sighted."
Mr Brownlee says the evidence of the past decade shows the number of vehicles on the road has increased despite rising fuel prices
The Smart Transport Network says what is short-sighted is the Government's current approach to transport spending.