The 1NZ crown is now beyond his reach but Whanganui driver Hamish Auret has plenty left to drive for in the 2018-19 4x4 National Trials after a hot and hard afternoon in the Waikato on Saturday.

Auret and co-driver Paul Barnes finished fourth both overall and in D-Class at the Whatawhata course near Hamilton, in blistering hot conditions where 12 of the 44 trucks were unable to complete the 28 obstacles.

The pair also had a scary moment where they rolled on one obstacle and Barnes suffered a knock to the head, feeling unwell for the rest of the round and ultimately having to get medical clearance from the St John's ambulance staff to continue.

"He certainly didn't want to back up after that either," said Auret.

Advertisement

"He's as tough as old boots."

Normally Auret would appreciate the challenging obstacles which had been set for the course, thanks to the advantage in power from his 7.0-litre Corvette engine.

However, the extreme heat in the Waikato countryside was taking its toll on men and machines waiting in the valley's, where the sun-baked ground was rock hard.

"It was like rolling down on concrete. It was a day to drive and survive," said Auret, who kept up a steady intake of fluids.

'It was a really tough day at the office, we were lucky to finish.

"We struggled with overheating and engine issues. We had to get towed back to the pits three times."

Even the top drivers completed only a handful of obstacles without giving away any penalty points.

Auret finished with 677 points, distant fourth behind the men on the podium in Auckland's Jarred Biggs (614), Waikato 4WD vice-president Neville Mather (581) and defending national champion Scott Biggs (549).

Advertisement

Scott Biggs picked up his third win out of the four rounds, after twin brother Jarred had won the last round in the South Waikato in January.

Auret, who had to miss the opening round due to recovering from a broken leg, has now had finishes of second, sixth and fourth, and is out of mathematical contention for the championship.

Jarred Biggs has a third place and a win to his name, while Mather now has two podium finishes, but both would require Scott Biggs to have real misfortune at the next two rounds to move past him on overall points.

Auret said while their rollover cost them a podium on Saturday, even without it they still would have finished second place to Scott Biggs, meaning their thin hope for staying in the title hunt would have been gone anyway.

However, Auret can still finish 2NZ or 3NZ for the season.

"It just keeps us in it," he said.

A finish in the Top 10 takes on added importance this season, as it relates to Dan Cowper's private Suzuki Extreme Challenge event on April 28 at his Turakina farm, later to be screened on TV3.

In previous years, entry was by Cowper's invitation, but for the fifth edition of the event he has announced the Top 10 drivers from the national series will qualify.

Cowper is currently acting co-driver for Palmerston North's Stuart Earle, who purchased the truck off him in January.

Earle finished fifth on Saturday, although well back from Auret, with 778 penalty points, having come eighth in his first time behind the wheel at the previous round in January.

The next round will be hosted by the Bay of Plenty 4WD Club on March 16.