NSW motorists will pocket a refund of as much as $125 on their green slips as part of the state government's overhaul of the compulsory car insurance scheme.

The partial refunds for Sydney motorists, who pay the highest prices for green slips, will average $70 while country drivers will pocket about $30.

Sydney motorists stand to receive refunds of up to $125. Credit:Peter Rae

In all, about $300 million will be returned to motorists in NSW from December in partial refunds on what they have paid this year.

Finance Minister Victor Dominello said the overwhelming majority of the state's motorists would receive some refund and a cheaper insurance premium next year.