The Transport Minister says people who drive diesel cars can expect their road user charges to increase.
The Government has decided to accept most of the findings of an independent review group on road user charges.
Transport Minister Steven Joyce says the review found light diesel vehicles contribute the least to the roading system, compared to their use of it.
Mr Joyce says while this will have to change, any increase will be phased in, probably from October.
Two-thirds of the review's 33 recommendations have been accepted, including retaining road user charges instead of introducing a diesel tax.
Mr Joyce, who drives a diesel car, says he is keen to see the present system modernised and simplified.