Arnold promised to retrofit his Hummer so it can run on hydrogen, but his vow is too late for some protestors: As he pledged to sign an executive order to build a network of hydrogen fueling stations along the state’s highways by 2010, about two dozen protesters chanted, “A Hummer Isn’t Green,” so loud that it was difficult to hear Schwarzenegger’s speech. Michael Warnken, 28, of Santa Barbara, a Schwarzenegger supporter who tried to rip a megaphone out of the hands of a protester, was arrested and was being held in the county jail, said Sgt. Chris Pappas. The Hummer is listed as one of the “Meanest Vehicles for the Environment,” which continues the tradition of attributing human characteristics to SUVs. Find out if your car is mean or green. But remember, smaller more fuel-efficient SUVs called “crossovers” are all the rage now. The crossover is the fastest growing auto segment, and this change in consumer preference could mean a peaceful resolution to the SUV wars.