The 2007 Toyota Tundra was among the most eagerly awaited new vehicles of the past decade: a rising automaker's ultimate challenge to established competitors.

The Tundra struck at U.S. automakers' last stronghold: full-size pickups. It was widely expected to stomp them into dust.

Instead of a triumph that pounded the final nail into Dodge, Ford and GM's coffins, Toyota's first full-size pickup has struggled.

Hampered by disappointing fuel economy and recalls, the Tundra was among the first cracks in the veneer of invincibility that Toyota built over decades.

The Tundra is far from the cause of Toyota's woes, but the big pickup may be symptomatic of what went wrong when the automaker's headlong rush to boost sales met a management culture in which all major decisions were made in Japan.

The wheels didn't come off Toyota's revered engineering and quality-control systems the same day the automaker decided to invest billions of dollars in its first full-size pickup, but the Tundra is a nexus of the automaker's current problems.

Toyota executives called the Tundra the most important vehicle the automaker had ever introduced in the U.S., but the program stumbled from the start. Its disappointing fuel economy was a shock that undermined Toyota's image of technical superiority. It struggled to reach it sales goals and fell victim to early recalls. The Tundra is among the vehicles affected by both of Toyota's current unintended-acceleration recalls.

Toyota spent years developing its first true full-size pickup, tooling two assembly plants to build it. The current Tundra, which competes with the Chevrolet Silverado, Dodge Ram, Ford F-150 and Nissan Titan full-size pickups, went on sale in 2007. It replaced a smaller pickup of the same name Toyota had introduced in 1999.

"The Tundra just didn't meet the expectations of people who owned F-150s and Silverados," said Stephanie Brinley of consultancy AutoPacific. "It wasn't the best in its class, and the Toyota halo didn't transfer from cars like the Camry."

While U.S. automakers had built a succession of poor cars in the 1980s and '90s, Chevy, Dodge and Ford pickup owners were generally satisfied.

In addition to underestimating the competition, Toyota's timing was lousy. After years on the upswing, the market for big pickups faltered just as the Tundra went on sale in 2007. Gasoline prices spiked from a national average of $2.11 a gallon to more than $3 as the Tundra hit the market.

Toyota invested more than $4.5 billion in the two Tundra assembly plants. It then spent an unspecified amount to retool its Princeton, Ind., plant to build other vehicles when Tundra sales sank to just 79,385 last year.

Carmakers don't disclose their costs to develop a vehicle, but it's safe to say engineering added at least $1.5 billion to the Tundra's tab.

Few of Toyota's customers were clamoring for a big pickup powered by a 381-horsepower, 5.7-liter V8 engine. Toyota built its reputation on small, reliable cars and high fuel economy.

"The decision to build the Tundra was driven more by Toyota's desire to be a full-line manufacturer than to please its existing customers," Brinley said.

The resources that produced benchmark vehicles like the Prius and Camry were spread thin as the automaker pushed to become the world's largest automaker.

Toyota President Akio Toyoda admitted to Congress that the desire for growth led to Toyota's current woes, but the automaker's Japan-dominated culture created some of the Tundra's shortcomings, said Jim Hall, managing director of 2953 Analytics. "The cultural gap to develop a big pickup is huge for Japanese companies," he said.

Toyota spent more than a decade edging into the market with two smaller pickups before the 2007 Tundra, only to have its self-proclaimed most important vehicle ever for the U.S. run headlong into stronger competitors, a stumbling economy, a market shift away from pickups and now the company's own quality problems.

With around $6 billion spent on the Tundra and more than 8 million vehicles now recalled for a variety of defects, it's worth asking whether Toyota's big pickup was a considered strategic move or a costly detour.