The ANZ bank's Truckometer,which uses traffic volumes as a proxy to map quarterly economic growth, shows traffic flows remained flat in February.
The Heavy Traffic Index measuring flows of trucks on 11 roads and rose 0.3%.
ANZ says while the economy grew solidly in the last three months of 2012, it has not been a strong start to this year.
Senior economist Sharon Zollner describes the situation as "patchy". She says the high dollar is making life tough for exporters while the picture among New Zelaland's trading partners is still very mixed.
The more volatile Light Traffic Index, which gives a six month lead on GDP growth, declined 1.6%, almost wiping out January's gain, and suggests activity will fade by mid-year.