A car’s “claxon” should not be used on New York streets “except as a sound signal of imminent danger,” according to the city’s administrative code. The minimum fine is $350, higher if one of those hapless “DON’T HONK” signs are nearby.

Yet according to the police, a mere 286 summonses were issued last year for honking; only 448 such summonses were handed out the year before that.

“It’s a staple complaint we get on 311 and our e-mails: ‘Cabdrivers honk too much. Can you stop them?’ ” said David S. Yassky, chairman of the city’s Taxi and Limousine Commission.

But what would a “low-annoyance” horn sound like? No one seems to quite know for sure. Nissan, which must deliver the new cab by late 2013, had no immediate answers when a reporter called, and even city officials had trouble specifying what they wanted.

“Less grating,” Mr. Yassky said when asked to describe his ideal horn. “Less sharp and jagged.”

How about mellifluous?