i have had mcs for 7 years and from my personal experience with air purifiers for cars and other person air purifiers, i have to say that they dont work very well at all in a car. i went through a lot of cars before i found out what needs to be done to make trips with very few reactions, and the most important things that you have to do is find a car at least 2 years old but not so old that it has rich exhaust emissions.make sure you have cloth interior. and one of the most important thing that needs to be done is have all the engine gaskets changed that are leaking oil,then use a non toxic degreaser such as aerospace 303 citrus based cleaner, and clean the oil off the engine then hose the engine down, make sure you dont have any exhaust leaks, and make sure the tailpipe emissions is clean and within limits. always drive with the windows closed to keep out as much exhaust as possible. if you follow these instructions you will be able to travel in you car more normally with very few reactions.