Some 7.8 million American cars are suspected of having faulty airbags that can explode and send shrapnel flying through the passenger compartment. The recall was first announced early last summer, but took on urgency when Federal officials told consumers this week they should have the bags replaced "immediately."

But, as our car critic Susan Carpenter notes, most dealers don't have the parts to perform the replacement. And even if they did, the huge number of cars needing service will create an enormous backlog. She gives us some background on the Japanese firm that supplied the airbags, and says while it's still unclear who will pay for the recall repairs, consumers won't have to foot the bill.

Also this week, Carpenter reports that falling gas prices are putting the brakes on sales of hybrids, electrics, and other alternative fuel vehicles.  Meanwhile, Americans, seeing lower prices at the pump, are snapping up SUVs and pickups.

And she reviews a new, web-based company that claims it has the technology to make selling your car easier and more profitable. Carlypso sets up test drives, and installs a GPS tracker so the test driver doesn't disappear with your vehicle.  

Susan Carpenter joins Take Two each Thursday for The Wheel Thing.