Are motorcycles more environmentally friendly than cars? Ask most people that question and their initial response would probably be “yes” because motorcycles are more fuel efficient, and they release less CO2.  But is that the whole story?

MythBusters‘ Jamie Hynerman and Adam Savage are going to find out on the Emmy-nominated show’s fall season premiere, Sept. 28 on the Discovery Channel. With the help of Kent Johnson, an emissions expert from the University of California, Hynerman and Savage will analyze the emissions of three cars and three motorcycles representing the 1980s, 1990s and 2000s, to find out which mode of transportation is greener.

The show will be interesting to watch because MythBusters does a good job of making science entertaining, but we’re afraid the results won’t fall in favor of motorcycles.

That’s because carbon dioxide (CO2) is not the only kind of gas emitted by internal combustion engines. CO2 gets most of the attention but vehicles produce other kinds of pollutants including carbon monoxide, nitrogen oxide and hydrocarbons.

According to certification documents from the California Air Resources Board, a 2012 Yamaha R1 produces 0.7 g/km of carbon monoxide. Meanwhile, a 2012 Toyota Sienna minivan produces 0.3 grams of carbon monoxide per mile. Since a mile is equivalent to about 1.6 km, that translates to 0.18 g/km, nearly a quarter the amount of carbon monoxide produced by the R1.

In fact, the CARB’s standards for cars are much stricter than they are for motorcycles. A vehicle such as the Sienna has to produce less than 1.7 g/mile (1.06 g/km) to get CARB approval. By comparison, the standard for motorcycles such as the R1 is 12 g/km.

Of course, these are test figures in controlled environments. The boys at MythBusters will likely be testing under real world conditions (because riding or driving vehicles is more entertaining than watching them on a dynamometer) so we’re curious to see what their results will be.

[Source: UC Riverside, CARB]