Labour's truck ban could cover 0.7 per cent or 7 per cent of New Zealand's motorways - depending on who you listen to.
There was some confusion about the impact of the policy, which was unveiled by leader David Cunliffe on Tuesday.
It would block trucks from using the outside lane on three or four-lane highways in an attempt to reduce congestion, especially logjams during public holidays.
Economic Development Minister Steven Joyce mocked the policy in the House yesterday, saying it would apply on just 50km or 60km of New Zealand's 11,000km of state highway.
This contrasted with the New Zealand Transport Agency's analysis. The agency said that there were 840km of highways with three or more lanes - 160km in Auckland.