There's a Joke going Around the Auto industry that the only car auto makers soon will be able to sell in California will be Fred Flintstone's foot-powered Flintmobile.

But by 2012, even Flintstone's ride may not pass muster in the Golden State because it is not equipped with the special windows and low-rolling-resistance tires that likely will be required.

Thumbing its nose at the Obama Admin.'s view that fuel-economy regulations should be dictated by the federal government, not the states, the California Air Resources Board recently adopted a law requiring new cars sold within its borders be equipped with windows that reflect heat-producing rays from the sun.

Next on the agenda are rules calling for low-rolling resistance tires and a standard for lower-viscosity motor oil.

So it's official: CARB now is designing our cars. Because California buys more vehicles than any other state, and because it is costly to custom-build vehicles to accommodate individual state laws, we can assume the rest of U.S. consumers may have to accept these design specifications, too.

Using solar-control glass, tires that roll more smoothly and thinner oil to improve fuel economy are not bad ideas.

They certainly are better than CARB's push earlier this year to require heat-reflecting paint as a means of improving fuel efficiency. It shelved that idea after it was informed such paint has not been invented yet.

Solar-reflecting glass has been invented and already is used on some vehicles in Europe. It keeps cars noticeably cooler in hot, sunny weather and saves a little gas by making the air conditioner work less.

Glass suppliers such as Pittsburgh Glass Works and Southwall Technologies tell Ward's they are thrilled by the prospect of getting business from the new law and say they easily can supply the technology to auto makers in the U.S.

The problem is CARB regulators don't know anything about the business of building and selling vehicles and only care about improving fuel economy. Unlike automotive engineers, they are not required to care about safety, durability, customer satisfaction or unintended consequences.

Heat-reflecting glass currently is considerably heavier than conventional tempered glass. If it is used for all the glazing on large, top-heavy vehicles such as SUVs or minivans, it could increase the risk of rollovers.

Exatec, a plastic component supplier, is developing lightweight polycarbonate windows and backlites that could save gas by lowering vehicle weight, but it may not be able to meet upcoming solar requirements. Could fuel-saving part specs actually hurt the introduction of new efficiency-enhancing technology?

Low-rolling resistance tires improve mileage, but they generally do not perform as well as other tires in slippery conditions or during high-speed maneuvers. This raises safety issues and the specter of falling performance-car sales because they all will be equipped with hard, skinny rubber.

Engines filled with low-viscosity oil may not last as long and could suffer performance problems.

CARB regulators have forced positive change in the auto industry with tough regulatory actions for the past 30 years, but this new strategy of telling auto engineers how to hit fuel-economy targets in addition to mandating them is bizarre and potentially dangerous.

CARB needs to give up trying to design vehicles or be stopped before its arrogance and ignorance cause real harm.