Driving Drunk To Mean Loss Of the Vehicle
New York City Police Comr Howard Safir announces that, starting next month, cars of people arrested on drunken driving charges in city will be seized on spot and later forfeited if drivers are convicted; officials say state law currently allows forfeiture of vehicles owned by repeat offenders, but it is rarely enforced; critics warn that with forfeiture practices coming under increasing scrutiny because of abuses by law enforcement agencies, any attempt to expand forfeiture is likely to face tough legal challenges (M)