Though its headlights point further than other indicators, Zollner cautions that the Truckometer has limitations.
"It will not fully pick up the boost to GDP coming from the Christchurch rebuild," she said.
The limited data available so far for the current quarter have been mixed.
"Corroborating the Truckometer, we've seen the April performance of manufacturing index tank and weaker house sales," she said.
"On the other hand, business confidence has remained robust, and electronic card transactions data for April were solid."
Light vehicles provide the best lead to activity six months ahead.
"It would appear that willingness to buy and drive a car is the ultimate measure of true, money-where-your-mouth-is consumer confidence," Zollner said.
Heavy traffic is more contemporaneous with GDP and provides a useful robustness check on predictions.