If the auto industry thinks it’s going to have a hard time meeting U.S. fuel-economy mandates or European limits on carbon-dioxide emissions, it ain’t seen nothing yet.

Hold onto your hat with both hands folks – the regulatory push barely has begun.

I just had a fascinating discussion with three leading environmentalists in California, with the goal of getting an idea of where the next round of CO2 regulations is headed. After all, as goes California, so goes the nation – and ultimately the world. And what the California environmental lobby really wants is corporate average fuel economy of somewhere between 70 and 100 mpg (3.4 L/100 km and 2.4 L/100 km).

Auto makers will wring their hands in anguish because the investment needed to hit those kinds of numbers is going to suck up much of their cash for decades to come. But they better figure out how to deal with it, because there is no question the regulations are coming.

I spoke with Roland Hwang, vehicles policy director for the Natural Resources Defense Council; Mark Bernstein, managing director of the University of Southern California’s Energy Institute; and James Lents, president of the International Sustainable Systems Research Center.

What worries these environmentalists is the lack of progress on reducing greenhouse gases. Even most of the countries that signed on to the 1997 Kyoto Protocol are watching their CO2 emissions rise. And these guys say we need to achieve an 80% reduction in CO2 to reduce global warming.

For those of you who, like me, are skeptical of man-made global warming, it’s too late. We’ve already lost the public debate. Any auto maker that fights this movement will get pounded with an unceasing barrage of bad press. So what to do?

First, there’s a need to publicly embrace this environmental movement. That’s a massive risk for most auto makers because if the greens get the idea you’re eager for their ideas, they’ll push for more, faster. But they also are willing to get the government to cough up billions to help the industry get much of the funding it needs. I say: Be the first in line to get the money.

Second, put the pedal to the metal to come out with plug-in hybrids. The greens are absolutely ga-ga over plug-ins. And guess what? They’ll be perfectly happy with nickel-metal hydride batteries that only deliver a 15-mile (24-km) pure-electric range. No need to wait for lithium-ion batteries that provide a 40-mile (64-km) range. In fact, for them, the Holy Grail is a plug-in that runs on cellulosic ethanol.

The auto industry faces a massive challenge to re-tool for the regulations that already are on the books. But once auto makers meet that, there will be no time to catch their breath. The push is building to blow past the current regulations. And those that are ready will be the big winners.

John McElroy is editorial director of Blue Sky Productions and producer of “Autoline Detroit” for WTVS-Channel 56, Detroit, and Speed Channel.