Z Energy says petrol consumption is falling in relation to increasing availability of broadband.
While more fuel-efficient vehicles and rising petrol prices have also contributed to consumption falling from its 2007 peak, Z's chief executive, Mike Bennetts, said demand was more sensitive to broadband connectivity than these traditional factors.
"People are doing less discretionary motoring and that may be about the price but what we have found is quite a strong link between broadband connections and fuel consumption," he said.
"People are doing online shopping and Skyping granny rather than making the fortnightly visit."
A 1 per cent improvement in broadband connectivity is estimated to cause a drop of 200 million litres a year in national fuel demand, more than the impact of GDP growth, population, fleet turnover, vehicle efficiency and the petrol price.