Business Week writes Car rental service Zipcar has been seeing the sort of growth most CEOs only dream of: Now operating in seven East Coast cities, revenues at the Cambridge (Mass.) company zoomed to $7 million in 2004 from $2 million in 2002. But last year big growth turned into big headaches. Customers using the company’s telephone reservation system started to experience delays, even when they were requesting basic information about the service. Rather than simply add more telephone operators, CEO Scott Griffith thought it made more sense to tie the phones to the Web in an automated system that could recognize customers and pull up their account information immediately. Already, he credits the higher level of customer service provided by the Web-enabled phone system for $3.5 million in sales.