Sustainability at General Motors is something we've covered repeatedly at GreenBiz.com, from zero-waste factory floors to innovations in alternative fuel sources. But shifting an enormous company like GM is no quick feat, and even the last 3 months have suggested that a sea change is underway in how American car-buyers in particular are choosing their vehicles.

I recently spoke with Terry Cullum, the director of Corporate Responsibility and Environment & Energy at General Motors, about the company's long efforts to improve the environmental performance of their vehicles, as well as how GM is looking ahead to make successful predictions about the long-term market. I began by asking Terry how the near future looks for GM, with its all-electric Chevy Volt scheduled for release in 2010, how a global company addresses regional preferences and its options for alternative fuels.

Matthew Wheeland: Are there solutions that you're tailoring to specific countries, to specific regions within countries? Are you sort of playing all over the field to see what works best at this point?

Terry Cullum: Yeah. I think it's a little of both quite frankly. I think we're looking at the energy infrastructure in the various parts of the world in which we sell vehicles. Probably the best example is looking in Brazil where they have an abundant supply of sugar cane and it's no secret that the Brazilians have moved very aggressively into the biofuel area and I believe somewhere around 95 percent of the fueling that's done in Brazil is with biofuels. So there's one where the natural resource that's available is certainly something that makes economic sense in terms of moving into - for the existing, the car park.

So that's an example of you want to apply the energy source that makes the most sense for that region. But yes, for right now what we're trying to do is we're trying to look at - because we're developing global architectures, we're trying to look at many different options to deploy and it would be dependent on again the regions in which we are going to deploy the technology so there's lots of options that we're looking at. A lot of options on the table in trying to deploy advanced technology where it makes the most sense.

MW: Let's talk a little bit about the broader shift in what consumers are looking for in cars. I think the news recently was that GM is taking a second look at the Hummer line which I think has long been the poster child for the least, you know, fuel efficient, least environmentally friendly vehicle. There was news earlier this week that Ford had an SUV plant that was gonna have to sit idle for nine weeks because of slacking demand.

How does a company as large as General Motors respond to this change in demand quick enough to meet it? I mean obviously this didn't come out of nowhere but it has picked up really rapidly just in the last few months.

TC: Sure. I think obviously it's a direct result of fuel prices escalating at the rate that they have. And hitting points where it now makes a difference with the consumer. So I think we've hit that.

And so a company as large as General Motors, we like to be large and nimble is what we' like to be. And when we saw that the trend was moving in that direction it was clear that we had to make fairly aggressive moves to adjust to that change in consumer demand. And that's why you saw the announcements relative to some of our full-size sport utility and truck plants, and that's where the discussion around the Hummer brand was initiated. So you have to be as nimble as you can be even though you're big. It requires a tremendous amount of manufacturing flexibility and engineering flexibility and management commitment to make these changes. But the management commitment is there and we certainly have the manufacturing expertise and the engineering expertise to take on the task at hand.

So over the next couple years you're going to see changes as a result of $4.00 and above gas prices.

MW: Now I have a question sort of about policy. It's not all that well formed in my mind so forgive me in advance. Barack Obama, the presumptive Democratic nominee, was at a General Motors plant earlier this week I believe talking about manufacturing, talking about how to bring these jobs back to keep those factories open even if people aren't buying Hummers. If there is something else to take that place on the manufacturing lines.

What would be your hope for General Motors in terms of how to grow market share and lower café averages to improve environmental performance and overall impact of the cars? What's sort of your hope for General Motors along those lines?