Singapore, one of the most expensive places in the world to buy a vehicle, has announced it will freeze the number of private cars on its roads from next year but vowed to expand public transport.The growth cap for all passenger cars and motorcycles will be cut from 0.25 percent a year to zero with effect from February, the Land Transport Authority (LTA) said.The affluent city-state of 5.6 million people already imposes a quota on the number of vehicles sold and the number on its roads, and h