If he really wants to reduce traffic congestion, Mayor Bloomberg could cut the number of cars in New York by almost a quarter if he followed the example of the pink protectorate, where even a billionaire can own only a single car.That one-car-per-home restriction has been in effect for decades in Bermuda, where the mayor has a multimillion-dollar getaway that carries no more entitlement autowise than a studio apartment.Here in New York, more than half the 3 million-plus households have no car registered at all. About 1 million, or about one-third, have just one car. Such numbers have long made us the greenest city in America in this regard.But more than 300,000 households have two or more cars registered.And some 80,000 have three or more.If just the 80,000 with more than two were restricted to one, that would cut the number of cars by more than 160,000. The same restriction applied to those with two could cut another 300,000, for a total of 460,000 cars."Whoa!" said an official at Transport Control in Bermuda on hearing this figure.And these startling numbers are based on the 2000 census. Many more multiple car owners have since moved into areas such as Park Slope in Brooklyn, where burgeoning traffic long ago killed the venerable game of stickball.One recent arrival was seen to park on Carroll St. the other day in such a way as to take up two parking spots. He later returned with a second car. He moved up the first and backed in the second."Did you really just do that?" he was asked."I have two cars," he replied.Meanwhile, other local residents were driving around and around, looking for parking. A recent study by Transportation Alternatives found that 45% of the traffic in Park Slope at any given time is cruising for parking spaces. The "average curb saturation rate" was put at 94%, meaning only 6% of the spaces were vacant at any one time.The study might have added that this fume-spewing cruising also greatly increases the aggravation suffered by all drivers. Too many of the new arrivals inch along when looking for parking as if they are the only people who matter. Never mind that somebody behind them might be actually trying to get somewhere.As one remedy to the Park Slope parking crunch, the study recommended the implementation of residential permits such as issued in London and across the Hudson River in Hoboken. The London system restricts parking to the zone where you reside. Authorities there have sought to reduce further the number of cars by declining to increase the number of permits for some properties that are divided into additional apartments. Some new houses are awarded no permit at all.London also provides the model for Bloomberg's plan to charge drivers for entering Manhattan below 86th St. during the busiest hours. The mayor is definitely a guy who knows money, and he tells us this will raise hundreds ofmillions of dollars to be invested in public transportation along with matching city and state funds.A Bermuda-like limit combined with a London-type fee might make New York an example for all to follow. Scamsters would no doubt try to beat the one-per-household rule by registering out of state, as many now do by securing Pennsylvania plates at bogus addresses to beat high insurance rates and city summonses.The registration scam is particularly popular in the less yuppified sectors of Brooklyn, the borough that has nearly a quarter of all accidents in New York State involving cars with Pennsylvania plates. The number for 2004 was 1,098 in Brooklyn of the 4,495 statewide.Such figures already demand a crackdown and stiffer penalties. Even with the scamsters, we could figure on at least a 20% drop in the total number of cars in this city.We might still be a long way from becoming Bermuda, but we could do our bit to save the planet. We might even get in a game or two of stickball.