Lauren Fix is the Car Coach. She answers reader mail and comments on our Facebook page. You can see all of Lauren Fix's advice at www.laurenfix.com.

Dear Car Coach:

My fuel economy has lately dropped off, and I really don't want to get rid of the car. I just passed the emissions test. The cost of gas is killing me and there has to be a reasonable solution. Any thoughts?

The Car Coach Responds:

Passing emissions is critical to keeping your car on the road. Usually, if you fail an emissions test it's related to exhaust gases. I think I have a good solution for you.

Have your mechanic check your Positive Crankcase Ventilation (PCV).

Here's a bit of history, in the 1960's, the PCV system appeared on new cars. Before your mechanic automatically replaces the PCV with the one provided by the automaker, ask about possibly installing a different product--the DynoValve, which is designed for use in automotive gasoline powered vehicles; it replaces standard PCV valves.

The DynoValve optimally regulates the flow of engine blow-by gases with an electronically controlled switch. Put more simply, it makes your car breathe more efficiently and captures emissions in such a way that fuel and oil is saved. The DynoValve, I believe, can better eliminate the vacuum problems associated with today's standard PCV valves by optimally regulating the flow of engine blow-by gases.

The company's tests, which have been accepted by the EPA, show there was a reduction of all exhaust emissions, while simultaneously reducing fuel and oil consumption. There was an MPG improvement by at least 10% in most makes and models, reduced emissions from vehicles by up to 90%, and improved engine performance. You can read for yourself at dynovalve.com.

Here is a caution, though. If your car is still under warranty, you have to discuss with your mechanic whether installing the DynoValve rather than the standard PCV valve will void your warranty.

Dear Car Coach,

Do you think that there might be some truth to this story? My husband has a practice of opening the windows all the time before turning on the air conditioning in the car. I thought he was just doing a man thing (smile).

Here is his thought process: the car dashboard, seats and air fresheners emit benzene, a cancer-causing toxin.

In addition to causing cancer, [we believe] Benzene poisons your bones, causes anemia and reduces white blood cells. [We believe] prolonged exposure will cause leukemia, increases the risk of cancer, miscarriages and kidney damage. I hope you can tell me what this is about.

The Car Coach Responds

This is an urban myth.

This item about the dangers of benzene supposedly emitted by automobile components has been widely misunderstood. Urban myths are everywhere, the internet is full of facts and stories, and research on your own will give you the answers to some of them.

Your car's air conditioning system itself is not producing benzene. There is a theory around that says to open your windows upon entering your car to vent the alleged accumulated benzene fumes.

How much truth is there to this warning? Evidence suggests an association between exposure to benzene and an excess risk of leukemia, as noted by the American Cancer Society (ACS): A considerable number of human studies provide evidence linking benzene and cancer. But most of these cases with high levels of benzene exposure in the chemical are from the shoemaking, and oil-refining industries in which workers are exposed hourly and over a period of years.

But do automobiles really produce potentially cancer-causing levels of benzene? A 2001 study of commuter exposure (in both cars and buses) in Korean urban areas found some relationship between automobile use and exposure to benzene.

The study found that traveling by automobile increased exposure to a number of deleterious compounds, including benzene, but the primary factor in this regard was the fuel used by the vehicles, not internal components such as dashboards.

The study also found that exposure levels were significantly higher during the winter months, which suggests that automobile air conditioning use is not a major factor in benzene exposure. The study itself did not establish a connection between commuter exposure to benzene and the onset of cancer.

Here is a better reason to open the windows before turning on the air conditioner: Opening the windows will vent the hot air out of the car. After you have done that, turn on the AC and the cabin will cool off faster.