OTTAWA (Reuters) - American junkyards are filling with millions of worn-out cars, and consumers will have to replace them sooner or later.

That bodes very well for major Canadian auto parts makers, whose shares have largely stagnated in recent months after a year of furious growth.

Analysts say the stocks look set to push ahead in coming years, making them a good play for patient investors.

Canada's three biggest parts suppliers — Magna International, Linamar, and Martinrea — have demographics working in their favour, they argue.

US light vehicle sales haven't kept up with the annual scrappage rate of 12.5 million vehicles. But the population is still growing and people still need to get to work and school.

"Any Canadian auto parts supplier that's tied to North American light vehicle production is going to see explosive earnings growth in the next couple of years," said Morningstar analyst David Whiston.

"Last year was the first year we scrapped more than we sold since at least World War II ... I don't think that's sustainable when the number of licensed drivers in the United States increases by one percent every year. Also, you've got vehicle fleets getting to all-time highs age-wise."

Chicago-based Whiston is keen on Canada's parts makers because they're profitable even with US auto sales near historical lows.

As the industry has pulled back from the brink, Magna's share price rose about 2-½ times. It closed at C$87.17 on Friday.

Linamar surged tenfold and trades at C$19.71. And Martinrea jumped about fourfold to C$7.84.