People will do the right thing when they are asked, and they will do it much more willingly than when they are told they must do it, Benjamin Franklin astutely observed. "Where heavy burdens are too laid on them, it has been found useful to make it, as much as possible, their own act." Franklin's observation is true of individuals and of corporations, even when the burdens aren't so heavy. Simple cooperation toward a common good often depends on how participants are asked.

Car companies today not only can build cleaner-breathing cars than the government mandates, they do build them. Some of these clean green machines are available in all 50 states, most are available in some of the states that adopt California's emissions rules, and a few are available in California only.

The problem is that mainstream consumers are largely unaware these cars exist. With so many marketing messages to convey in order to drive showroom traffic, manufacturers have found limited opportunity to tout these special models to the consumers who may be interested. All of this potential is providing very little of the benefit it could. Drawing inspiration from Franklin, we could encourage sales of more of the cars that make the least pollution without any onerous laws, requirements or fines.

Here's how: The Environmental Protection Agency need only create a certified label system that conveys to buyers in a self-evident way the relative cleanliness of each car's exhaust emissions. This would give carmakers a tool with which to brag about their accomplishments in helping to clean up pollution, and it would give environmentally conscious buyers a way to know whether they are in fact buying a vehicle that is good (or bad) for the environment.

The EPA and the National Highway Traffic Safety Administration are redesigning fuel economy labels and have asked for input from consumers as to what they want to see. Versions of the labels under consideration can be viewed at fueleconomy.gov/feg/newFuelEconomyLabel.jsp.

To hear some of the so-called greenies tell it, any vehicle with all-wheel drive and an enclosed rear cargo area is an Earth-devouring, anti-Christ SUV, but in fact some SUVs are far cleaner than some cars available. An emissions labeling system could help derail the SUV-hating bandwagon by illustrating that pollution isn't determined by bodystyle.

Today, the EPA and California Air Resources Board have a bewildering array of acronyms referring to various levels of exhaust emissions and evaporative emissions. Consumers don't know a PZEV from a PEZ dispenser and they shouldn't have to. Only a bureaucrat would want to learn the all the various LEV (Low Emissions Vehicle) buzzwords, and there is no obvious hierarchy to show that one label is better than another. The solution? A voluntary labeling program defined by the EPA for manufacturers to follow that works along the same lines as the National Highway Traffic Safety Administration's hugely successful program of awarding one to five stars for a vehicle's safety performance.

New cars need not achieve any particular rating in NHTSA's crash tests as long as they meet that agency's most basic requirements. The rating program is entirely voluntary, but car makers work diligently to earn five-star ratings because that is what consumers demand. There is no law, and there is no government punishment involved. But because consumers can easily spot the safer cars, manufacturers make more high-scoring cars.

The EPA launched a similar labeling program in 1992 for appliances and computers. The Energy Star program required that manufacturers meet certain low-power consumption requirements to be eligible to affix the Energy Star label to their products. The feds even threw in a little incentive by telling them that the government would buy only Energy Star products in the future, helping kick-start demand for the label. As a result, last year Energy Star products saved enough energy to power 15 million homes and saved consumers $7 billion, according to the EPA. Even allowing for some governmental fudge factor, it is still an impressive accomplishment, without the threat of any penalty whatsoever.

In Germany, the ADAC (akin to the AAA in the U.S.) already has such a labeling program that could serve as a model. We should outline an EPA program of assigning "stars" (or green leaves, or whatever icon of measurement is deemed appropriate) for varying levels of emissions. Everyone would understand that four green leaves beats two. Yes, there are those who believe that the government should mandate every aspect of our lives and jail any of us who fail to live by the standards they would dictate. But Franklin and our other founding fathers knew better. The best way to lead people down the right path is to simply ask them to follow.

Franklin did his part by devising a clean-burning stove to heat homes after living in smoggy, sooty 18th century London. There's no reason we can't follow his self-reliant example.

-Dan Carney

A veteran automotive journalist, Dan is a regular contributor to IntelliChoice and Motor Trend.