Cars emit more than just carbon dioxide and water. Some of the other molecules that are emitted include Benzene, 1:3 butadine, carbon monoxide, nitrogen oxide, sulfur dioxide, and ozone. These molecules are emitted when the car is actually running and by evaporation while the car is parked. As you can see there are many molecules that cause the global warming threat from cars. Although, some people think it is better to take the bus, whereas a bus (as found in a study by The National Environmental Technology Centre (NETCEN)) can emit the equivalent amount to 128 cars (http://www.abd.org.uk/exhausts.htm). Other good sources for this information are http://esa21.kennesaw.edu/activities/smog-cars/doe-veh-pollutants.pdf or http://www.fhwa.dot.gov/environment/aqfactbk/page15.htm , where it shows how the emissions given by trucks and cars have both decrease. Cars have decreased much more than trucks but they both have gone down. Although no matter what we drive or use (car, truck, bus, hybrid, etc.) the emissions will still be there.
As written on the main page, there are ways of making your current car run better than a hybrid. Just make sure that the maintainance is kept up on your car and that it is running properly, emitting the least amount of CO2.
