The Delhi government yesterday said the Supreme Court order restricting registration of petrol and diesel private non-commercial vehicles to 1,500 per month in the National Capital Region was "unimplementable" and it would soon move the court for its modification."The order directing registration of cars on a first-come-first-serve basis is unimplementable as there are 21 registration points in the NCR, of which nine are in the capital," Delhi chief secretary Omesh Saigal said.