A rise in demand after the lifting of Covid restrictions has driven earnings and market share for the country's biggest fuel retailer, Z Energy.

The company, now part of the Australian owned Ampol Group, had A$83 million (NZ$92m) in pre-tax earnings for the five months ended September, with the bulk of that in the June-September quarter.

A group trading report says there has been a smooth transition to the import model after the closure of the Marsden Point oil refinery in February with no supply disruptions.

It says Z Energy has increased its market share by two percentage points on the previous year ago, which it expects to hold on to.

"Covid-19 mobility restrictions continued to impact retail volumes for much of the period but lifted towards the end of the quarter," the company says in a statement to the NZX.

"Fuel sales for the quarter were 969 million litres reflecting the ongoing improvement in demand through the quarter, with falling crude and product prices being positive for fuel margins. The non-fuel earnings growth strategy also continued to deliver promising results."

Ampol did not give any further detail on Z's trading performance, such as the convenience stores or the costs of ending its biofuels venture.

However, it says Z has booked net proceeds of NZ$126m from the sale of a 49 per cent stake in 51 freehold properties to an unlisted company.

Z Energy is also reported to be carrying on with its plans to look at alternative fuels and other energy transition projects, including importing sustainable aviation fuel on behalf of Air New Zealand.

Ampol completed its $2 billion takeover of Z Energy in May, which required it to divest the Gull Energy chain previously Ampol's only New Zealand business.

-RNZ.