Costco has revealed its petrol pricing for its service station at Westgate, which opens this morning.

The US giant will sell 91 for $2.50 per litre, 95 for $2.60 per litre and diesel for $2.10 per litre.

Photo / Michael Craig

The pricing is below the nearby Pak'nSave, whose service station is selling 91 for $2.68, 95 for $2.84 and diesel for $2.29. according to Gaspy.

The catch: the self-service station's 27 pumps are only available to Costco members.

An annual membership costs $60 or $55 for business.

So far, the only way to register is to join a queue of up to 90 minutes at Costco's temporary admin office at Westgate, but the retailer says an online option is on the way.

The first wave of cars came through at 9.20am.

The service station is opposite the $100m Costco store at Westgate, which the retailer's Australia-NZ boss Patrick Noone says will open in late August.

As in Australia, Costco is partnering with Mobil.

In its recent report into supermarket competition, the Commerce Commission said, "Woolworths NZ [owner of Countdown] also told us that Costco is seen as a "destination shop" and that they have seen analysis from Australia suggesting that Costco stores have in-person catchment areas of approximately 25km."

That's for general shopping. Across the Tasman, a report for the New South Wales state government found Costco influenced petrol prices in a 5km radius around its stores.

Costco also plans stores in Wellington and Christchurch, subject to the performance of its Auckland operation.

Costco's 2021 annual report says its 636 service stations account for 9 per cent of its US$163 billion revenue worldwide (as of December 2021, Costco had 828 stores or "warehouses" as it calls them, including 677 in North America, 29 in the UK and 13 in Australia).

A 2020 Houston Chronicle report said the giant retailer at times uses fuel as a "loss-leader", selling at 20c to 30c cheaper per gallon (3.7 litres) than traditional service stations to attract customers to the rest of its business. And in a March 11 article on the Ukraine crisis highlighting "cheap gas" at Costco and other big retailers, the Wall Street Journal said, "Big box retailers are counting on drawing in consumers with cheaper gasoline and then having them leave with an armful of groceries too."

- Chris Keall and Anne Gibson, NZ Herald