It’s really only one sentence, but it’s a very meaningful one. EPA Administrator Lisa Jackson said April 17 that she “proposes to find that the emissions of [greenhouse gases] from new motor vehicles and new motor vehicle engines are contributing to air pollution which is endangering public health and welfare under section 202 (a) of the Clean Air Act.”

If that statement stands—there’s a 60-day comment period—then the EPA (at a virtual standstill on this issue while Bush was in office) could soon be in the tailpipe regulation business. Should we care about this? You bet. And a lot, too, since it will determine what kind of car you can buy.

According to the Environmental Defense Fund, “EPA action would be far more protective of the environment and more cost-effective than any Department of Transportation fuel economy standards because EPA has the authority to economically leverage the benefits of emission reductions across the entire motor vehicle system—cleaner fuels, more efficient combustion systems, mitigating [refrigerant] air conditioning emissions, tires, etc.” Other eco-nonprofits weighed in as well.

Tailpipe climate emissions can’t be controlled with a simple add-on filter. Our choices are switching to electric vehicles (EVs) or making new cars dramatically smaller and more fuel-efficient. The EV revolution is underway, but will take a while, and automakers who’ve gorged themselves on profitable SUVs are finally—and glacially—preparing to introduce small cars. GM’s got one (the Chevrolet Cruze) and so does Ford (the Fiesta). Chrysler will borrow fleets of them from new partner Fiat, if that deal goes through.

So if climate laws regulate the auto industry, the showroom could look like a transplant from Europe, with small cars dominating the landscape. And they’ll be complimented with a plethora of hybrid, plug-in hybrid and pure EV offerings from a dozen high-tech startups—Aptera, Bright Automotive, Think Global, Fisker, Tesla, and many more.

Tease photo: AquaColor/iStock

Jim Motavalli ( @jmotavalli ) writes about cars, technology and the environmental world to anyone curious enough to ask.

EPA says tailpipes pollute
The EPA's proposed rule opens the door to widespread tailpipe regulation. Get ready for a new generation of smaller, more fuel-efficient cars!