A regulation change this year means that the fastest cars will run in the worst road conditions on day one of rallies.
The FIA ditched the qualifying stage for this season, with running order now decided on championship position - which leaves Polo R WRC drivers Jari-Matti Latvala and Sebastien Ogier first and second on the road for next week's opening gravel counter of the season in Mexico.
The Leon-based event is notoriously slippery for those first on the road, with the grip levels improving with every car that passes over the central American stages.
M-Sport driver Hirvonen reckons such unfavourable road conditions for the VWs might be the only way rivals can beat them this year.
"If they have to start first on the road in some of the events like Mexico, Portugal and Sardinia, then you might stand a chance, but even then it's going to be really tough," he said.
"That's the only game plan we can have.
"Volkswagen is really on their own pace. I think it's clear to see that they can do whatever they want in all of those three cars.
"The car is one or two steps ahead of everybody else, but, of course, they are good drivers as well.
"It's going to be a fight for the podium with the rest of us. If nothing happens to the Volkswagens then it's going to be tough to win any rally this year."
Hirvonen's team principal Malcolm Wilson agreed with his driver.
"Like Mikko says, the best chance for us probably comes in the running order - especially if the events all adopt the guidelines which state that 40 per cent of the [competitive] mileage should run before you can reseed. This has to help," said Wilson.
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