Nissan Chief Executive Carlos Ghosn drove quietly out of the Japanese automaker's soon-to-open headquarters Sunday in the first public viewing of its new zero-emission vehicle. It was the first time the external design was shown of Nissan Motor Co.'s environmentally friendly electric automobile, set to go on sale in Japan, the U.S. and Europe next year. Nissan has promised that the Leaf, which goes into mass-production as a global model in 2012, will be about the same price as a gas-engine car such as the 1.5 million yen ($15,000) Tiida, which sells abroad as the Versa, starting at about $10,000.