He hit repeat this year, winning the Supersport 300 class again and adding the Supersport 600 crown in Taupō at the weekend.
Having already clinched the 300 title the previous weekend at Hampton Downs, Buchanan’s steely focus was on the larger-capacity class crown, but he did not have an easy time of it at Bruce McLaren Motorsport Park.
In fact, lifting the Supersport 600 trophy came down to the final race of the season and it was an all-out battle involving Buchanan, Yamaha Racing Development team-mate Jake Lewis and Rogan Chandler.
Buchanan was sweating at the start of the last race as "the tyre wasn’t coming to me".
"But the longer I got into the race, the tyre started to come on a bit and when I saw a gap between Jake and Rogan, I was able to go for it and really tried to put the hammer down.
"The defining moment was when I hit the front and I tried to put as many fast laps in as I could."
Having only swung his leg over a Yamaha YZF-R6 four months ago, becoming the national 600 champion in his rookie season did not feature in his early season expectations.
It was not until round four at Teretonga Park that he started to believe he could claim the championship.
"To actually win it this year was an unexpected surprise," Buchanan said.
"I’m definitely proud of winning dual titles. I did the same thing with the Supersport 150 and 300 classes in 2021, so to do it with the Supersport 300 and 600 was really nice."
Several crashes in the Supersport 300 class at Taupō were not the way he wanted to finish his season in this class, however, and Buchanan said he felt very lucky he got the championship wrapped up at Hampton Downs.
The 16-year-old rider headed to Europe on Sunday night for his third overseas campaign.
Yamaha Motor New Zealand motorsport manager Josh Coppins said it was a "huge achievement" for Buchanan to win double titles.
"I feel like having him on both the YZF-R3 and YZF-R6 bikes has really helped him progress and will put him in a great position for his international season," Coppins said.
"Jake rode really very well all weekend but unfortunately he is up against a very determined, very talented young lad with the world at his feet."
