[Editor's note: This story is the last of a three-part series on how the U.S. presidential election could impact the greentech industry. Read the first story, Presidential Picks Cast Solar Ballots, for a look at what the new president will mean forsolarpower, and the second article, Ethanol, Farm Industries Split on Candidates, exploring how biofuel companies could be affected by the White House change.]

Of all the green technologies mentioned in the presidential campaigns, cars may have received the most attention.

And why not? New car technology is sexy, and easier for the average American to relate to than, say, demand-response software or bioengineered biofuel enzymes.

It also could have a significant impact on climate change. Transportation makes up about 33 percent of U.S. carbon-dioxide emissions from fossil-fuel combustion, according to the Environmental Protection Agency. A 2006 report from the nonprofit Environmental Defense found that American vehicles emit nearly half the world's greenhouse gases from automobiles, according to the Los Angeles Times.

So both Democratic candidate Barack Obama and Republican candidate John McCain have made cars a visible part of their platforms.

Automotive research company CSM Worldwide said in August that the two candidates' platforms diverge sharply "where the rubber meets the road."

"It may seem like the candidates' positions are closely aligned, but they actually have radically different approaches to the [national fuel-economy] standards, the vehicle technologies they champion and the support they're willing to lend to automakers," CSM senior economist Charles Chesbrough said in a written statement.

McCain in June proposed a $300 million prize for an electric-car battery that costs 70 percent less than current technology and could help carmakers "leapfrog" commercially available plug-in hybrids and electric cars. He also has called for up to $5,000 in tax credits for consumers buying zero- and low-emission cars and has proposed higher fines for car companies - such as BMW, Porsche and Daimler - that fail to meet national fuel-economy standards.

"Whether it takes a meeting with automakers during my first month in office, or my signature on an act of Congress, we will meet the goal of a swift conversion of American vehicles away from oil," McCain said in a speech in June.

Meanwhile, Obama supports raising fuel-economy standards by 4 percent each year and has proposed a $4 billion aid package - made up of loans and tax credits - to help U.S. car manufacturers retool their manufacturing facilities to meet the standards.

He also has called for a $7,000 tax credit to help consumers buy cars with new technology, such as plug-in hybrids, and has proposed a target of getting 1 million plug-in hybrids on the roads by 2015. 

"At the turn of the 20th century, there were literally hundreds of car companies offering a wide choice of steam vehicles and gas engines," Obama said in a speech in August. "I believe we are entering a similar era of expanding consumer choices, from higher-mileage cars, to new electric entrants like GM's Volt, to flex-fuel cars and trucks powered by biofuels and driven by Michigan innovation."

Whichever candidate wins the White House, the auto industry is in for continued difficulty, Chesbrough said, adding that higher vehicle prices would lead to lower sales as customers buy smaller vehicles and keep their automobiles longer.

"These and other factors are going to keep industry volumes and profits under pressure," he said.

Eric Fedewa, vice president of powertrain forecasting at CSM, added that the industry is making "massive investments" on borrowed money to meet the stringent fuel-economy targets already on the books, and indicated that the auto industry would likely favor McCain's proposal to enforce the standards over Obama's proposal to raise them.

"Increasing [the standards] would only increase the risks facing the industry," he said.

Of course, either higher standards or higher penalties to enforce current standards would benefit companies with more fuel-efficient technologies.

And green-car groups, such as CalCars.org, which advocates for hybrids that can be plugged into the wall for more miles per gallon, already are cheering the election as a win.

"On Jan. 20, 2009, whether Sen. Barack Obama or Sen. John McCain is elected president, plug-in hybrids will have an advocate in the White House - and a staff that understands their benefits for economics, energy security and the environment," the group states on its Website. "We expect either candidate will make a priority to accelerate [plug-in hybrids'] commercialization."

Plug-in hybrids got a plug in September, when Congress approved tax credits for the vehicles as part of the $25 billion auto bailout.

CalCars founder Felix Kramer said his group's key priorities will be to get those credits extended, to expand them to include safe conversions of regular internal-combustion vehicles into plug-in hybrids and to get whichever candidate is elected to commit to federal purchases of plug-ins for government fleets.

Both candidates have called for greener federal vehicles.

However, Fedewa cautioned that while plug-in hybrids are "the Holy Grail for fuel economy," not everybody agrees they are the answer.

He added that it's unclear whether $4 billion for research and development -- and $7,000 incentives for buyers - will be enough to bring plug-in hybrids and other technologies into mass production and make them affordable. After all, General Motors plans to sell its Chevrolet Volt plug-in hybrids at a loss in 2011, which is expected to be the vehicle's first full year of production, CSM said.

Regardless of who wins, the new president will have his work cut out, said Thilo Koslowski, lead automotive analyst at Gartner.

"The whole issue of the environment and climate change is going to be an issue for any president," he said, adding that the environmental challenges combined with the current economic challenges won't make for an easy term.

Any time the economy weakens, people raise concerns about whether it's the right time to invest in green technologies, Koslowski said.  

"There's good evidence to believe the government is working in that direction, if you think about the $25 billion invested into the auto industry to help retool," he said. "It is on the right path, but we will have to see how tight the economy will get and how much that will play in its thinking [about the environment]."

While he said he believes plenty of new green-car technologies exist that could make good economic sense, incumbents might decide to deter green initiatives in this difficult financial time. He pointed to news last week that Chrysler is discontinuing the production of its not-yet-released hybrids and that General Motors Corp. is postponing much of its research and development.

"Car manufacturers are trying to scramble to survive, and surviving probably means maintaining what you have instead of investing in new areas before you can actually recoup costs or make money from [them]," Koslowski said. "It's pretty rough right now for all the big auto manufacturers."

All in all, the economy is likely to have a bigger impact on green-car technology than the election, because if people lose their jobs and don't have money to invest in green technologies, the industry could stall, he said.

But the government certainly can make a difference, he added.

For example, if politicians can create more compelling reasons to upgrade to new technology - such as a German initiative to eliminate taxes on low-emission cars - they could boost the industry.

"If there is evidence of increased consumer interest in green technologies, I think the government also will be much more inclined to invest in tho se new technologies," he said.

The question is, after all the bailouts and other expenses, how much money will ultimately be left for the government to invest in greener transportation, he said.

"Really taking a look at how those investments can help grow jobs and help address the climate issues would be the right approach, but there are also many other initiatives vying for investment dollars," he said. "Given the economic challenges, there certainly is a danger that some of the early focus the government has had on the environment might get lost. And that would certainly be a loss."