Big 3 dominance slipping as competition heats up

With auto sales in 2015 expected to move close to or above 17 million vehicles for the first time since 2001, it looks like the auto industry is finally back to where it was 14 years ago.

But the numbers tell a different story.

IHS Automotive compared the U.S. market share for the top eight automakers this year with the top eight auto companies in 2000.

The conclusion?

The sale lead of the Big Three—especially GM and Ford— is a far cry from what it was in 2000.

Read MoreThe most popular luxury vehicle is...

Back then, GM, Ford and Chrysler sold more than two-thirds of the vehicles in the U.S.

Today, they sell fewer than half of all new models.

"There's been a steady decline in market share for the Big Three," said Tom Libby, sales analyst with IHS Automotive. "They've lost their dominance, and other brands have become more competitive."

One reason the Big Three sell a lower percentage of new vehicles in the U.S. is because each company is smaller with fewer dealerships and brands.

Oldsmobile, Mercury, Plymouth and other brands that were part of the Big Three stable in 2000 have gone away, along with dozens of dealerships that once sold GM and Chrysler models.

Read MoreAmericans on the verge of buying 1 million pricey cars

Meanwhile, foreign automakers have expanded their lineups and marketing.

"Hyundai has been able to pick up market share thanks to marketing campaigns that really stood out from the competition," said Libby. "The Altima is an example of why Nissan has picked up share. It used to be a weak midsized sedan. Now after being redesigned it's very competitive with the Toyota Camry and Honda Accord."

While General Motors' leading market share could end the year under 18 percent, IHS is forecasting the GM will remain America's top car company for the foreseeable future.

In fact, IHS believes the top for automakers in America will likely hang onto their spots over the next four years.

"The quality of the models coming out from the Big Three will help them keep their market share," Libby said. "Every vehicle they build now can stand up to any other model in their category."

Read MoreFalling gas prices not slowing hybrid production

Correction: This story has been updated to reflect Chrysler's market share in 2000 and 2014.

Questions? Comments? BehindTheWheel@cnbc.com.