PERTH, Australia -- Newly-crowned world champion Marcus Gronholm collected his fifth win of the season and a hat-trick of successes in the Rally of Australia after cruising to a comfortable victory.

The Finn brought his Peugeot home 57.3 seconds ahead of teammate and compatriot Harri Rovanpera to earn his third successive win in the Perth-based event after dominating from the opening day on Friday.

Gronholm, who secured a second world title in New Zealand earlier this month, opted for caution on the final day as he preserved his lead before setting the fastest time on the final 'Bannister North' stage.

"I have had no problems," said Gronholm, who is now 43 points clear of teammate Briton Richard Burns in the standings.

"When you've got a good lead, you have to keep pushing to a certain level to keep your own concentration and also make sure the guys behind don't get too close.

"That's what I've been doing. But I have the feeling that I could possibly have gone a little quicker than I have done."

Rovanpera snatched second from Subaru's Norwegian Petter Solberg after setting the pace on the opening three stages of Sunday's final leg in a pine plantation complex.

The Finn, 24.4 seconds behind Solberg overnight, benefited as the Subaru driver made the wrong tire choice for the opening two stages and held on to second to help Peugeot to their ninth one-two finish of the season.

Solberg said: "I was trying very hard but I knew it would be difficult to beat the Peugeots today. The stages are flat out the whole time in fifth and sixth gear and that helped them."

Four-time champion Finn Tommi Makinen came home fourth for Subaru but was later excluded after race stewards found his Impreza WRC to be underweight.

Makinen's car failed a number of repeated weight tests during Sunday's final leg with the Subaru below the minimum 1230 kilograms stated in the FIA regulations for a World Rally Car.

Team principal David Lapworth said Subaru had decided against appealing "in the interests of the sport" but promised to hold a full investigation into the situation.

Lapworth said: "We have decided to accept the judgement and will not appeal the stewards' decision."

He added: "The rules in this area are very clear and we know that the cars are likely to be weighed at the end of every stage.

"So we clearly believed that the car was at its correct weight throughout the event. We will be making our own investigation into this situation."

Makinen also vowed to look into the weight problem and said nothing deliberate had been done by the team.

"I don't understand what happened," Makinen said. "There was certainly nothing deliberate involved. That's just the way it goes sometimes and you have to accept it."

Makinen's exclusion promoted Ford pair Spaniard Carlos Sainz and Estonian Markko Martin to fourth and fifth respectively, with Skoda's Finn Toni Gardemeister scoring the final point in sixth.

Sainz had earlier lost his overnight fourth place to Makinen on the second stage of the day, 'Bannister South', after rolling his Focus WRC when he hit a rock on the test.

"At a very slow first gear junction, the car hit a rock in a rut and just turned over," Sainz said. "It landed on its wheels and we only lost five or 10 seconds.

"But the turbo pipe was ripped off in the accident and we had to drive the rest of the stage with no boost which is why we lost more time."

Martin took fifth after team mate Belgian Francois Duval had crashed out of the event on the penultimate stage, 'Bannister West'.

Duval left the road midway through the 34.57-kilometer test. He severely damaged his car and was airlifted to the medical hospital in the service park.

Ford said Duval suffered a badly bruised thigh following a collision with a tree in the incident.

His co-driver Jean-Marc Fortin said: "Francois' door took the full impact ... the pain in his leg was too bad and we stopped."

Finn Toni Gardemeister brought his Skoda home a distant seventh before being promoted to sixth to score a vital point for the Czech marque.

Frenchman Sebastien Loeb, of Citroen, Skoda's Swede Kenneth Eriksson and Mitsubishi drivers Jani Paasonen, of Finland, and Austrian Manfred Stohl completed the top 10.

Hyundai's veteran Finn Juha Kankkunen was forced to retire on the final stage of the rally after his Accent WRC suffered loss of oil pressure midway through the test.