Believe it or not eBay Motors is the largest and fastest growing segment on the popular auction website. Last year $7.5 billion worth of automotive products were sold. That's out of $23 billion total for all of eBay. Business Week provides a Q&A with eBay Motors GM Simon Rothman about the endeavor. He assures us that eBay is as safe a place to buy a used car as the local classifieds. Still it's understandable that some buyers who are willing to spend $5 on a CD won't be as eager to spend $5,000 on a car.