True or half-true: The Internet already has transformed the way Americans buy their cars. The answer is: It depends. If you go by the number of actual sales made online, studies suggest the Internet's role remains marginal. A report issued in June by TNS Intersearch said just 4 percent of Internet habitués had bought a new car or truck online. That's consistent with a Gartner Group report in July that 3 percent of households had bought a new car online. But both these studies concur with a new J.D. Power and Associates report in saying people in the market for a car are making the Internet a routine part of the shopping process. The research firm says 54 percent of new-vehicle buyers now use the Internet "for help"—up from 40 percent last year. The main reason they do so, says the report, "is to find price-related information to help them negotiate with dealers." Thus, the Internet's main effect on car sales may be to alter the balance of power between buyer and seller. The online action is not confined to new-car sales. The Gartner Group found 32 percent of households that bought a used car or truck between September 1999 and March 2000 "used the Internet in their buying process," including the 1 percent who made the purchase itself online.