Take a look at Co-op America's page on the subject. Sign the petition to GM and Ford, and tell your local dealers to urge the company to do the right thing: make plug-in hybrids and electric vehicles. Also tell your congressional lawmakers to require more fuel-efficiency in future cars. Not in ten years. Now.
Of course, a change to more fuel-efficient vehicles only goes partway to solving our climate and congestion issues. We spend an incredible amount of money on our roads and parking lots and the real solution is to get people out of their cars and reclaim some of that lost land. We shouldn't assume that vehicle use will just keep climbing.We need to take active steps to reverse that trend. One way to do this is to start charging for parking! Check out this neat little powerpoint presentation by Donald Shoup, author of The High Cost of Free Parking. If the powerpoint file interests you you might want to get the book. It's amazingly readable and often funny, especially considering that it is entirely about parking.