The Australian Rally Championship leader's Mazda2 slid off the road and hit a tree during his first qualifying run in the Power Stage of the event.

Reeves and his co-driving sister Rhianon Gelsomino were unhurt.

ARC spokeswoman Katie Philps said it was first thought the car suffered only radiator damage, but closer inspection revealed the engine had been pushed back by the impact.

"There are now a lot of people who will be working through the night to get the car back up and running for the start of the rally on Saturday," Philps said.

Reeves remained positive his team would be ready.

The Power Stage is outside the rally itself and while worth bonus points, failing to finish does not rule him out of overall contention.

He holds a 34-point leader over Renault driver Scott Pedder after two rounds of the ARC and aims to extend his advantage this weekend.

The 25-year-old will wear a full-face helmet for the first time on the Sunshine Coast.

Reeves adopted the safety measure after his sister suffered minor burns to her face competing in a Rally America event in May.

“Rhi was involved in an incident where their car caught fire, and wearing a full-face helmet helped to protect her from serious burns,” he said.

“It’s for that reason that I’ve got a new lightweight Stilo helmet that felt really good during our test.

“I wore a full-face helmet when I was racing go-karts, and while they’re a bit hotter to wear, I’m sure I’ll get used to it quickly.”

After winning the opening two national championship rounds and having a successful test session this week, Reeves was confident of a strong performance.

He completed just six runs of the 4.5km test stage on Wednesday, happy with the set-up of his front-wheel-drive rocket.

“The car felt really good from the first run, so we didn’t feel that doing more runs than necessary was going to prove beneficial."

Reeves believes being consistent over the event’s two days will be critical in consolidating his lead.

“This event can be a car breaker, and with 20 points on offer for each heat, and 40 points for the overall winner, getting to the finish on both days will be important.

“Of course we want to win both heats, but winning overall here is the key, and that’s what our aim will be.”

The Rally of Queensland has 16 competitive stages and a total  distance of 237km.

Action starts on Saturday morning around Imbil and Kenilworth and continues until Sunday afternoon.

Reeves planned to miss the ceremonial start of the rally in Caloundra on Friday night to focus on getting his car back on the road.