A suggestion the devil is in the detail when it comes to the Greens' plans for zero emission vehicles.

The party wants to require all new imported light vehicles to have zero emissions by 2030.

Auckland University director of the energy centre Basil Sharp told Kate Hawkesby we're among the highest in terms of car ownership per capita.

"We hold onto our cars for an average of 14 years - so we have to deal with the status quo so to speak."

Sharp says our median incomes are lower than California - where there's a similar policy.

He says their federal and state governments offer rebates of up to nine-thousand dollars if you buy a zero emission vehicle