ByJohn S. McClenahen Sales of autos soared 5.5% in December, resulting in a 1.2% rise in overall retail sales for last year's final month, reveal U.S. Commerce Department data. Without the surge in car sales, retail sales would have been flat for the month. Retail sales totaled $308 billion in December, compared with $304.2 billion in November. "The data are consistent with about a 1.5% rate of increase in total real consumption in [fourth-quarter 2002] GDP and close to 3% excluding autos," says Maury Harris, chief U.S. economist at UBS Warburg LLC, New York. "That is actually a bit stronger than the 1% we have been assuming in our 1.8% estimate for total real GDP . . . ."