The PM said the move would ensure “Kiwis aren’t being charged more” for ACC without a good reason, and that the annual license and petrol levy will not increase.

Kiwi motorists are paying less at the pump, but cheaper fuel comes with fatal consequences, new research has found.

The Australian National University's Crawford School of Public policy has published a paper presenting the first detailed analysis of the effect of fuel prices on New Zealand's road toll.

The work, conducted by Paul Burke and Rohan Best, was prompted by the rise in New Zealand's road deaths in recent years, which coincided with a fall in fuel prices.

Using data from 1989 to 2017, researchers concluded lower fuel prices resulted in a higher road toll.

READ MORE: Fuel prices are forcing a change in habits

Between 2013 and 2016, fuel prices fell by about 23 per cent in New Zealand. During the same period, road deaths increased by 16 per cent, the paper said.

"Lower fuel prices appear to have contributed to New Zealand's recent uptick in road accidents, pushing against the long-term trend of improved road safety," it said.

ALDEN WILLIAMS/STUFF Fuel prices fell by about 23 per cent between 2013 and 2016, the research paper says.

Fuel prices hit record highs in recent months, costing up to $2.50 a litre for 91 unleaded. Recently, it has plummeted below $2, on the back of cooling international oil prices and a strengthening New Zealand dollar.

"When fuel prices are low, people are likely to drive more, exposing themselves to additional road accident risks," the paper said.

Lower fuel prices also freed up disposable income for things like alcohol, which could lead to more alcohol-related accidents, it said.

SIMON MAUDE/STUFF Greater Auckland founder Matt Lowrie says motorists take fewer discretionary road trips when fuel prices are high.

Matt Lowrie, founder of urban planning publication Greater Auckland, said motorists drove more conservatively when fuel prices were high.

"When people drive they don't have as much lead in their foot," Lowrie said.

People cut out discretionary trips they might take when fuel prices were low, he said.

However, Auckland motorist Maree Cotter said petrol prices had no effect on her driving behaviour.

"There's no connection between how I drive and the petrol that goes in my car. There's no relationship between them in some ways - we probably should have one - but there isn't."

Another driver, Doni Clarke, told Stuff she drove less when petrol prices rose.

"I feel like I don't use my car [as often]. I walk to work instead."

LAWRENCE SMITH/STUFF Auckland driver Doni Clarke says she drives less when petrol prices rise.

The paper said lower fuel prices could lead to an increase in road travel by young drivers, for instance, who were statistically more likely to crash.

Conversely, with high fuel prices, there was an increase in cyclists sustaining injuries, as cars were substituted for bikes, it said.

The annual total social cost of road crashes in New Zealand – including costs of injury – was estimated at more than $3.7 billion.

LAWRENCE SMITH/STUFF Motorist Maree Cotter says petrol prices have no effect on her driving behaviour.

Other factors which may have contributed to New Zealand's increase in road deaths included rising wages, international visitor numbers and smartphone and navigation device use.

The paper suggested road safety campaigns take fuel prices into consideration.

"It would make sense for road safety advertising expenditure to increasingly target cyclist safety at times when fuel prices are high.

"Greater focus on motor vehicle drivers, and on open-road driving, appears to be warranted when fuel prices fall."

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