There's a lot going on inside your vehicle at any given time, whether you're idling at a red light or driving at freeway speeds. Much of this activity involves chemical reactions that — while ...

You may also notice unusual exhaust smoke — thicker, darker plumes or even a strong smell. ... Ultimately, any or more than one of these issues can lead your Pilot to fail its emissions test.

Overall, the study suggests that if at least 15 percent of driving occurs in city conditions, electric vehicles produce less non-exhaust particulate matter emissions than gasoline-powered vehicles.