In 2030, a Hummer may sit next to a Ford Excursion in a museum exhibit, as children and old folks gawk at the amazing gas-guzzling display. They’ll be astonished that something as precious as oil could have been squandered in that way. The only way to create an alternative history is to figure some way to make these big behemoths sip fuel.

The word “hybrid” in big chrome letters on the side of a honkin’ truck doesn’t guarantee a thing. If the 2011 Chevy Silverado hybrid pickup gets just 21 mpg overall, and the BMW ActiveHybrid X6 just 19 mpg on the highway, it’s not worth the trouble, and there’s something seriously wrong with our approach to turning America’s favorite vehicles into green cars.

And that’s why Ford and Toyota (which actually made the monster truck at left) are collaborating on a new rear-wheel-drive hybrid system for SUVs -- they want to see if they can, together, eke out much better fuel economy numbers from the bug truck and SUV platforms. How about 30 mpg on the highway, without compromising the towing capacity?

There’s precedent for this. Although the company based at One American Drive in Dearborn didn’t like to talk about it, Ford traded patents with Toyota for the Escape Hybrid it debuted in 2004. And BMW worked with General Motors and Daimler on a $1 billion program (announced in 2006) to develop dual-mode hybrids that went on larger vehicles. That BMW X6 is a product of that collaboration. But as you can see, it doesn’t go far enough toward really goosing the fuel economy.

As Forbes describes it, the Ford/Toyota partnership grew out of a chance encounter between Toyota CEO and family scion Akio Toyoda and Ford wunderkind Alan Mulally at an airport. Toyoda obviously likes the personal touch, because his deepening relationship with Tesla Motors also turns on his apparently hitting it off with CEO Elon Musk.

Toyota knows a lot about hybrids, having produced 3.3 million of them since 1997. And Ford is a world leader in big SUVs, a category whose status is endangered by a tendency to guzzle gas. This new partnership is, in part, about keeping big trucks viable in the 21st century. Bill Visnic, an analyst, told CNN, “This is a pretty big deal. This is two major players in this market saying we need to develop something to keep pickups and SUVs relevant,” he said.

As it is, Americans part with their large vehicles reluctantly. The Ford F-150 is the number one bestseller in the U.S. now. But separation is inevitable, because people are being hit with intense pain at the pumps. Here’s a chart sourced from BNET showing how much people are paying to fill up large SUVs with $3.80 a gallon gas: So much for the classic American family “are we there yet?” vacation. At $3.55 a gallon, a round trip from Chicago to Yellowstone National Park in a Chevy Suburban with the 5.3-liter V-8 would cost $650, and each stop would require shelling out $126, or about what you’d pay for the night’s lodging at the Holiday Inn.

So it makes great sense that Ford and Toyota are collaborating on big trucks. They’ll still be going at each other hammer and tongs as competitors in other areas, but here they can work together and make some breakthroughs. We need the work to succeed.

Jim Motavalli ( @jmotavalli ) writes about cars, technology and the environmental world to anyone curious enough to ask.

Two amigos: Toyota and Ford
The two big automakers will work together on creating hybrid versions of gas-guzzling SUVs and trucks. If they don't, fuel costs will price Americans out of the