Optimism returns to the Detroit auto show Monday as the industry looks forward to strong sales growth after years of painful restructuring, a deep economic downturn and serious supply shortages.

"It'll be upbeat, it'll be intensely competitive," said Michelle Krebs, an analyst with Edmunds.com.

The Detroit Three automakers will be fighting to hang onto or even expand recent market share gains achieved by radically revamping their product offerings even as they shed unprofitable brands and models.

Toyota and Honda are looking to regain ground lost when their inventories were crippled by the March 11 Japanese quake and tsunami.

"The problem for Toyota and Honda is that some of their market share losses are potentially permanent losses because the competition is so much better," said Jesse Toprak, an analyst with TrueCar.com.

"Consumers who would have bought a Toyota or Honda ended up getting something else and realized these cars are as good or better."

Korean carmakers Hyundai and Kia - which have been the big success story of the downturn after winning over consumers looking for good value - will be working to keep up their momentum.

German automakers will be pushing at the higher-end of the market.

BMW and Mercedes managed to overtake Toyota's Lexus brand as the best-selling luxury brands in the United States in 2010 amid the Japanese automaker's supply problems, and will be jostling to hold their ground.

Volkswagen also has ambitious goals to more than double its US sales and overtake Toyota and GM for the top global sales spot.

There ought to be plenty of new customers to lure into showrooms this year.

Nearly one in every five vehicles on the road is over 10 years old. That's around 50 million vehicles that will need to be replaced in the coming years.

US auto sales are expected to grow to 13.5 to 14.5 million vehicles this year from 12.8 million in 2011 and 11.6 million in 2010.

That's still down significantly from the 15 to 17 million vehicles sold annually in the dozen years leading up to the 2008 crash, but solid enough growth that GM, Ford and Chrysler should continue to post rich profits.

"I think this pace of growth is good for the industry and for the country," GM's sales chief Don Johnson said after GM posted a 14 percent gain in 2011 US sales Wednesday.

"It gives the industry the chance to really institutionalize the discipline that has allowed us to prosper at lower sales volumes."

The show will also celebrate a remarkable turnaround for the Detroit Three.

Chrysler - which has been steered by Italy's Fiat since emerging from a government-backed bankruptcy - swung into a profit of $211 million in the third quarter of 2011 after years of bleeding balance sheets.

GM, which also underwent a government-backed bankruptcy in 2009, hauled in $7.1 billion in the first nine months of 2011 after posting a $4.7 billion profit in 2010.

Ford, which survived the downturn without resorting to government aid, has posted ten straight quarters of profits totalling $16 billion after a massive restructuring effort.

More than a dozen automakers will vie for the attention of 5,000 journalists with the launch of at least 40 new models on Monday and Tuesday, some ready to hit showrooms and others being rolled out as 'concept' cars to test the waters.

"It's going to be a big show for Honda," Krebs told AFP, noting that the Japanese automaker will be introducing a concept for the next generation of its popular Accord along with several new vehicles from its luxury Acura division.

GM will be introducing two small cars - the Chevy Spark and Sonic - which are aimed at winning over young 'millennials,' while Chrysler will show its first Fiat-based small car, the Dodge Dart.

Daimler's Smart will introduce a miniature pickup truck concept car that will be sure to grab attention.

Automakers will also have several swank sports cars on offer, like the Lexus LF-LC hybrid concept, the Mercedes SL roadster, and the new Porsche 911.

Green car fans will get a look at Volvo's plug-in hybrid concept, new hybrids from Mercedes and BMW, and an electric van from Nissan.

The North American International Auto show opens on January 14 and runs through January 23.