The independent petrol group, which originated in Gippsland, opened a 24-hour, seven-day self-serve diesel station in Horsham in November.

Endeavour group marketing manager Ross Gilberthorpe said the family owned company expanded into the Western District after recognising an opportunity to "shake-up" the market.

"Our director, Jeff Griffiths, always says: 'If it's a diesel price war, it's a party'," Mr Gilberthorpe said.

"Being a disruptor in a market is good because it takes out the complacency in business."

Mr Gilberthorpe said other fuel stations along Horsham's Golf Course Road had been matching Endeavour's prices from day one - with some dropping prices even lower.

Mogas was selling diesel for 137.5 cents a litre, while Endeavour and Petrogas had diesel priced at 137.9c on Friday afternoon.

Other petrol stations in Horsham were changing almost 10 cents more, with Liberty selling diesel for 145.9c, Woolworths charging 147.9c, and prices reaching 149.9c at BP and Caltex.

Asked how Endeavour could keep fuel prices so low, Mr Gilberthorpe said being an independent group meant more flexibility compared to bigger corporations in negotiating prices to buy and sell petrol.

"The customers have all been really positive about us driving the price down," he said.

Mr Gilberthorpe said the company planned to open more fuel stations in the region, with diesel sites planned for Stawell and Great Western next year.

"We know the rumblings are out there," he said. "People are asking: 'What are you doing in the west? You're upsetting people'," he said.

Mr Gilberthorpe said the company hoped to offer Wimmera farmers products and services such as fuel and lubricants in the near future.

RACV vehicle engineering manager Michael Case said RACV data indicated that the average price for diesel in Horsham was 146.3 cents a litre. He said Horsham diesel prices generally reflected the same price pattern as Melbourne, but were, on average, slightly cheaper.

"Competition is always good for keeping prices low, as having a choice of where you top-up is a win for motorists - as we are seeing in Horsham," he said.

"Motorists often suffer from lack of competition - especially in regional areas."

Mr Case reminded drivers to check RACVs fuel price website, which could help find the cheapest fuel in their area.

Mogas and On The Run head of fuel Rick Conti acknowledged that Mogas has been providing the same low cost, self-service model to diesel users in Horsham for years that Endeavour was now offering.

He said Mogas would also be opening two new 24/7 On The Run convenience stores in Horsham which would also offer a full range of fuel types.

The stores are scheduled to open in February 2020.

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