Ride along with the 'Car Talk' guys as they look into the future

I'm ready to sign up for my all-electric, nonpolluting, gorgeous-looking, super-efficient, 221 miles-per-charge Tesla Roadster. All I need is the $92,000 the sticker price shows. They're sold out for 2008, and the company's taking orders for 2009.

Failing that, I figure I'd look sharp in a Chevy Volt, with a battery pack good for 40 miles a day plus backup tank and hydrogen fuel cells. It's still in the dream-on prototype phase.

In the meantime, I'm enjoying a vicarious ride-along with Click and Clack, the Tappet brothers.

Tom and Ray Magliozzi, the guys of "Car Talk" fame, laugh and snort and cajole and insult on NPR radio each week until even those of us who know nothing about carburetors are in tears. I can't get enough. If you find yourself creating errands on weekends just to stay with the show you know their appeal.

They bring their act to a documentary hour, "Car of the Future," Tuesday at 9 on KCTS/9. A mix of serious science and good-natured Magliozzi madness, the "Nova" film slips talking heads and global-warming information into the fun without force-feeding.

Amory Lovins, chief executive officer of the Rocky Mountain Institute, a Colorado think tank, gives the brothers the scoop on the increased carbon emissions from cars and light trucks and how it affects the environment.

We see Lovins driving in the Rockies, gabbing around the table with staff and showing off lightweight but super-strong auto parts, all while explaining how to triple fuel efficiency.

Cameras follow Tom and Ray from one extreme to another in search of our automotive future: The Detroit auto show is about "primal thrills and horsepower." The AltWheels expo in Boston is about curbing our dependence on oil.

Older brother Tom can't help emitting an epithet as the Ford Mustang saleswoman pushes a car's outrageous horsepower. "Who needs that ----?" he asks. To watch is to giggle.

John Lithgow narrates, explaining the science of what carbon molecules do, how gasoline, electric and hybrid engines work, how hydrogen may replace carbon.

As the boys joke about various prototypes, they learn that changing an economy based on petroleum won't be easy.

There they are at rush hour in Reykjavik, Iceland, where gas is $8 a gallon, riding a hydrogen-powered bus. There they are, in hunter hats, learning about geothermal power as steam shoots up their pant legs.

And there, proffering corncobs in a lab that studies E85 ethanol, they find ethanol is good for fewer greenhouse-gas emissions but is not great for the environment.

Unfortunately for nonscience majors, they spend as much time in labs as in showrooms, hearing more about science than about what color those new cars may come in. But we come away better-informed.

Who knew that inefficient engine performance means less than 1 percent of a car's power is used to actually move the driver? Or that plug-ins cost four times less than conventional cars?

For now, the choice seems simple. What do you want, America, big horsepower or high fuel economy?