More than 200 trekkers headed north from Gunnedah to the historic town of Inverell yesterday, and are due to cross finish line at Port Macquarie today.

Organiser Bill Patrick said they are hoping to raise $1.5 million, which will go back to the RFDS for outback emergency retrievals, and vital outback primary health care.

And the travelling fundraisers are well on their way to hitting that target, with an auction in Gunnedah on Thursday night raising over $40,000, however Mr Patrick said the final figure would be more than $60,000 after Saturday night when more items are sold.

He said that was a record for their auction, which is just one of the money raising aspects of the trek.

"Trekkers also pay a participation fee - we say participation is a reward for raising funds - so all the money is raised before we leave town except for the auction night," he said.

"So we're not going around country towns that are already pretty strapped for cash and already supporting the Royal Flying Doctor asking for their money."

The outback car trek is the biggest annual fundraiser for the RFDS, and Mr Patrick said the support of the Gunnedah community was sensational.

"From motels to shops and cafes and service stations and caterers, everyone was great," he said.

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"All the council staff were also very helpful. All auction items were donated by participants, anything from a $30 bottle of port that went for $170, to a $600 bottle of grange that went $1500 to a barbecue that went for $10,000."

Nationwide the RFDS has a 'waiting room' of some 7.6 million sqaure kilometres and during the past year it has flown more than 27 million kilometres to help over 320,000 people - nearly one person every two minutes.

You can support the Flying Doctor by donating to the Outback Car Trek: https://www.outbackcartrekfundraising.com.au/