Senior Constable Warren Bunn, of the police Serious Crash Unit, said the driver had been heading south when his vehicle left the road at a right-hand bend between Turk Valley and Houhora Heads roads.
The car went through a fence and struck a "pretty substantial" tree. The 68-year-old local man was dead when emergency services arrived. The investigation was continuing but fatigue was a possible factor given the absence of brake marks.
The highway was reduced to one lane but remained open. The Pukenui Rural Fire Party was called to assist at 4am with the Kaitaia Fire Brigade returning in daylight to extricate the man's body.
Less than 48 hours earlier a 49-year-old Mitimiti man died while riding his motorcycle on the beach about 1km north of the isolated west coast settlement.
Mr Bunn said it appeared the man had been on his way to visit a friend about 7.30pm on Wednesday when his bike struck a log and he was thrown off. His body was found the next morning. The names of the two deceased have not yet been released.
The latest fatalities bring the Northland road toll to 21 for the year to date, with 14 of those in the Far North. The toll for all of 2016 was 27 with nine in the Far North.
Inspector Wayne Ewers, Northland road policing manager, said police could enforce the road rules and provide education, but it still came down to people making the right decisions.
"If you aren't going to use your seat belt you run the risk of being severely injured or even killed," he said.
"People have to take responsibility and look after each other, and make sure their mates and whanau have their seat belts on. I can't say it strongly enough. It's a repeated message but it's not getting through."
Of the 19 deaths before the two latest Northland fatalities, nine involved not wearing seatbelts, 12 featured drugs or alcohol and a quarter involved speed. All three played a part in some deaths.
"There have been some pretty clear-cut cases of people being thrown out of vehicles.
They'd be alive today if they'd clicked their seatbelts on," Mr Ewers said. "It's devastating for families, and also for the cops and emergency services who have to pick up the pieces and tell people their loved ones aren't coming home."
With its mainly rural roads, the common theme was alcohol and seatbelts, while in Whangarei speed was more often the culprit.
The latest deaths come just days after the launch of a renewed road safety campaign in the Far North, One Tear Too Many.
The campaign, by Far North REAP, features billboards calling on motorists to slow down, drive sober and buckle up, and is on the backs of the Kaitaia-based Petricevich bus fleet.
Nationally the road toll is also rising after dropping to 253 in 2013, the lowest since 1950.
