For the fourth consecutive year, U.S. automakers have exceeded the federal government’s requirements for greenhouse gas emissions, and they have also achieved record fuel efficiency. For Tesla Motors ( NASDAQ:TSLA ), China has been a promising market due to the government’s desire to reduce pollution, opening the door for a surge in electric vehicle (EV) demand. And while GM remains the top automaker in the United States, its sales decline 6.5 percent through April compared to a year ago, and it has lost a percentage point of its American market share, which dipped to 22.9 percent. If such a trend continues, since there is no way that Active Brakes Direct could do the trick, it would not take long before foreign automakers become more profitable than Detroit manufacturers. Mazda was well above average in the American Customer Satisfaction Index last year, but significant gains by other automakers has brought up …