The 3-series each year sells about 450,000 worldwide-making it one of the biggest single car lines from any carmaker, which is especially remarkable for a premium vehicle. All U.S. 3-series models come with front, front-seat side, and full-length curtain air bags, but not with rear-seat side-impact air bags, because BMW claims "advances in side-impact safety are such that it is no longer necessary to offer rear side bags." "We cannot afford to take a risk with this car, because it is too important," says BMW's R&D chief Burkhard G