The last time Cadillac, a symbol of American success, was the top-selling luxury car brand in the United States was in 1997. Since then, its executives have tried seemingly everything — from new models to new management to new marketing — to revive its flagging fortunes, with little to show for it.

Now, in its splashiest — and some might say most desperate — move yet, Cadillac is being split into its own business unit and will move its headquarters from Detroit to New York’s trendy SoHo neighborhood, General Motors, its parent company, announced on Tuesday. The hope, executives said, is that Cadillac can shed its stodgy image and recapture a mystique that melted away nearly two decades ago.

Johan de Nysschen, who joined Cadillac last month as its new president, from the Infiniti division of Nissan, said he discussed the move with G.M.’s leaders before taking the job. He said he was convinced that to reinvent the struggling brand, it needed more autonomy, more focus and more of a connection to what is cool and fashionable.

“If we stayed where we’ve been, nothing would change,” Mr. de Nysschen said in an interview on Tuesday.