Despite its impressive comeback in the United States, top management of Volkswagen AG is replacing Volkswagen of America Inc. President Clive Warrilow with Gerd Klauss, effective at year's end.

Mr. Klauss, currently president of Audi of America Inc., takes over a company with a healthy helping of momentum in the world's most competitive automotive market. Volkswagen's U.S. sales through the first half of 1998 are up 44%. In the same period its market share has jumped to 1.6% from 1.1% a year earlier. Company spokesmen offered no explanation for the change, nor what, if any, new assignment Mr. Warrilow will get.

When Mr. Warrilow took over in 1994, Volkswagen was recovering from its worst year in the U.S. since 1956. It was unclear whether the company would even stay here.

But an aggressive cost-cutting drive, including a 43% reduction in VWA's administrative staff, some bold and innovative new designs and the decision to build the New Beetle have helped bring VW back to life.