ANZ's Truckometer indicator fell last month, suggesting little momentum in the economy as the year ended.
The heavy traffic index tracks truck movements on 11 roads which historically have been well correlated with gross domestic product.
It fell 5.4 per cent last month, reversing gains in October and November.
ANZ chief economist Cameron Bagrie said the indicator had flagged the economy's softness in the September quarter and now suggested only modest improvement in the December quarter.
"We are left with the overarching impression of an economy where the clearest trend is still the lack of one," he said. "Monthly volatility is to be expected across indicators such as the Truckometer.