Toyota has been riding high on a green cloud of eco-friendliness with the American public since 2000. It was that year that Toyota introduced the first generation Prius. The tiny Echo-based compact sedan brought gasoline-electric hybrids to the mainstream.

Over the past few years, Toyota has expanded its hybrid portfolio and has seen its "green" image explode. Following the release of the first generation Prius, Toyota introduced a larger, mid-sized Prius hatchback in late 2003. Later, Toyota released a Highlander Hybrid SUV and a Camry Hybrid.

While the Toyota brand has focused on using hybrids to improve fuel economy, the Japanese auto giant's Lexus luxury division has been using the Hybrid Synergy Drive to boost performance. Increased fuel economy is still a benefit of Lexus hybrids, but the RX 400h, GS 450h and LS 600h L market the performance aspects of the additional electric motors.

Now, however, it appears that Toyota's honeymoon with environmentalists may be coming to an end. In a move that has angered the National Resources Defense Council (NRDC), Toyota decided to side with General Motors, Ford and Chrysler in opposing a proposed Senate bill that would require a corporate average of 35 MPG by 2020.

"Why is Toyota, a company that can make a car that gets 55 miles per gallon today, fighting a 35 mpg standard? If Toyota's "Moving Forward" motto is more than just empty words, the company must support a sensible increase in fuel economy to 35 mpg by 2020," said the NRDC in a statement on its website.

Instead, Toyota is putting its support behind a bill proposed by the House that would mandate targets of 32 MPG to 35 MPG by the year 2022.

“They have a green halo, justifiably, and yet unbeknownst to their customers they’ve joined forces with the Detroit Three to argue against greener standards,” said NRDC vehicles campaign director Deron Lovaas.

Toyota contends that the Senate bill is too harsh on auto manufacturers and will be tough to implement. “For the first time, the industry has actually come together for a fuel economy increase, and everyone is pulling together in the same direction,” said Toyota spokeswoman Martha Voss. “Toyota is working very hard behind the scenes to achieve the best standards possible, not only for the whole industry, but to meet the energy and environmental goals that we all share.”

Considering that Toyota's lineup of cars already average more than 32 MPG by federal regulations, many may wonder why Toyota would be opposed to a measly 3 MPG increase by 2020. Toyota's concern comes from the fact that the Senate bill would require a 35 MPG average from Toyota's entire vehicle lineup -- that includes gas-guzzling pickups and SUVs.

Toyota's apprehension becomes even clearer when the new Tundra full-size pickup truck comes into the picture. Toyota's Tundra has always played second fiddle to the biggest and baddest from Detroit, but Toyota's third attempt at the full-size market is starting to gain some traction.

The new Tundra packs a 381 HP V8 engine on its options sheet and records fuel economy numbers of 14 MPG/18 MPG city/highway in 4x4 guise. The problem is compounded by the fact that the previous generation moved a meager 124,508 units – Toyota is on track to break the 200,000 units sold mark for 2007 with the redesigned Tundra.

Toyota also announced cheaper trim levels for the 2008 Tundra which will further drive sales and lower the company’s fuel economy average. In addition, Toyota is looking to drive its truck sales even further with a redesigned Land Cruiser, Lexus LX 570 and Sequoia – all of which use the potent  5.7 liter V8 engine paired with a six-speed automatic transmission.

“They market every night the Prius and the Toyota Camry — we’re the green car, huh,” remarked Representative Edward Markey (Democrat-Massachusetts) who also happens to own a Camry Hybrid.  “Then watch the football games, and they’re marketing the Toyota Tundra — like the biggest vehicle ever made.”

“We’re actually going to name the vehicle the Tundra, after the thing that’s being destroyed in Alaska. How ironic,” Markey continued.

There is still room for improvement on Toyota’s end, however. The company is hard at work on a diesel engine for the supersized Tundra and the company plans to implement hybrid technology into all of its vehicles by 2020.