Australia's largest petrol station has opened in Melbourne's western suburbs, attracting keen motorists eager to grab a bargain.

Costco's petrol station backs onto the newly built warehouse in Ardeer, which will open its doors next month.

The supermarket giant revealed last year that it would be moving from Docklands to Ardeer in the city's west.

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Country Manager Chris Tingman said members would be provided with "exceptional savings".

Drivers will be able to fuel up from either side of their cars, thanks to the extra-long hoses available at 38 filling positions.

"Bowsers feature the latest pay-at-the-pump technology, giving members a seamless and convenient refuelling experience," Tingman said.

"Costco sees this region as dynamic and fast-growing and we believe that we can bring great value in relation to a wide range of products and services to the community".

The new site is open from 7am to 7pm, Monday to Sunday at 740 Ballarat Road, Ardeer.

The warehouse opens on April 9.

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