Bates, 24, wrapped up the championship in South Australia on the weekend with one round still remaining, the Coffs Harbour-based World Rally Championship event.

However, the eldest son of Canberra's four-times Australian rally champion Neal Bates had to dig deep to win the weekend round in the Adelaide hills, with arch-rival and former titleholder Molly Taylor using her Subaru's superior top speed to advantage on the Sunday stages and taking an early lead.

Bates and co-driver John McCarthy fought back during the day with the rally's winning margin the closest in championship history: just 0.2sec.

Harry Bates's younger brother Lewis finished third, rounding out a very successful weekend for the Canberra-based Toyota team.

For Neal Bates, whose small team built the two Yaris rally cars in his Hume workshop, having his son achieve such a high level of success in a car they've hand-built, is a hugely rewarding outcome.

"Going into the event, we tried not to think too much about the championship title, we just focused on what was ahead of us," Neal Bates said.

"I was a bit anxious because I know the fast roads suit Molly's Subaru and it was only because her car had a camshaft timing fault on Saturday that she couldn't use that top speed to her best advantage.

"And on Sunday, she came out and won two stages straight away, so we knew then we were in a real battle."

Neal Bates said his best recollection was that up until the weekend, he had the tightest winning margin in championship history of just 0.4sec, almost 20 years ago when he had a fierce battle with Scott Pedder's Mitsubishi Lancer.

But to finish just 0.2sec ahead over 97km of flat-out competition with the 1.6-litre turbo engine of his Yaris often banging on its top gear rev limiter at 191km/h, Harry somehow made that margin even tighter.

"My overall feeling at the end was 'oh, yeah, that's a relief'," Neal said.

With the championship safely in their keeping and near-perfect season result, Canberra's Toyota Gazoo Racing team will now sharply turn its focus to the world event in eight weeks, when the global, multi-million-dollar factory rally teams spare no expense or effort.

If the team hadn't won in Adelaide, it would have entered both cars in the Australian championship category.

But now they have the freedom to enter the car in the world championship category, which importantly gives the Bates team access to the same fast and grippy Michelin tyres that the factory teams run. The world championship control tyres cost about $500 each, and in one event each car will use as many as 24.

"There's a lot to think about now; we're definitely going to have go testing because the different tyres will mean we will have to change the set-up of the car quite a lot to make them [the tyres] work properly," Neal Bates said.

Canberra rally veteran and former ACT champion Trevor Stilling also had a successful weekend in South Australia, winning the two-wheel drive class in his Nissan Silvia.

Meanwhile, Canberra's future place on the national rally calendar has been secured with a three-year deal struck, making IT company Netier and accommodation specialists Abode Hotels the naming rights partners for the event through to 2023.