His Auckland rival Scott Biggs had another great day to win his third round of the campaign, conceeding only 359.55 penalty points for both the modified truck D-class and overall on the day.
However, this meant Biggs still finished runnerup for the season to Auret by a solitary point, having to rue a couple of bad rounds at the Pakaraka Rd course in Waikato and Mangaroa in Upper Hutt when he finished back in the pack.
Auret finished each round in the Top 5 with the exception of Sunday, including winning Mangaroa.
"If our worst nightmare came true, we'd still win it by a point, and that's what happened," said Auret.
"I'm just very lucky I did enough through the rest of the season.
"I feel sorry for Biggs, but I still feel like we deserve it.
"To get [the title] twice is really special, there is some pretty good competition out there."
The national championship remains amongst the Whanganui 4x4 contingent as Turakina's Dan Cowper was the 2015-16 champion, also ahead of Biggs, but did not enter this season.
Waikato 4x4 club president Greg McDell finished second to Biggs on Saturday by just 3.13 points, thereby coming third overall for the season.
The final round had probably the biggest turnout of trucks for the entire series, which included a couple of Whanganui drivers who had not entered the previous rounds.
Auret said he was pleased to see such a big crowd watching, as some of the proceeds for the event were donated towards the Rescue Helicopter service.
"They looked like nice, big hazards, I was gutted not to get to try them."
Unfortunately for Auret's fellow Wanganui 4WD Club member Kevin Hermansen, he was not able to retain his C-Class national title after a series of electrical problems in the engine saw him struggle through the day.
Coming in with a narrow series lead in Auret's former truck, the gutted Hermansen had to settle for fifth in his class, and 26th amongst all trucks, after conceeding 872.25 penalty points.
However, Whanganui still got a share of the C-Class title as Wanganui 4WD Club president Paul Chapman is the co-driver for Wellington's Phil Conwell, who clinched the championship with an excellent 462.26 score - winning the round and coming fifth overall on the day.
Whanganui's Grant and Reneé Harrison came sixth in C-Class for the round, 27th overall, but still received reward for a tough season when they were recognised as the Best Presented Vehicle for the Central Zone.
Mike Gee-Taylor entered D Class and finished eighth, plus ninth overall, with 557.76 points, while Dan Cowper's father John Cowper finished 19th in class, and 24th overall, with 835.61 points.
Looking ahead to 2017-18, Auret will get the transmission fixed and then begin maintenance on the Corvette truck to sort out any wear and tear, before preparing to try and make it back-to-back titles.