TOKYO, Dec 18 (Reuters) Nissan Motor Co, Renault SA and Mitsubishi Motors Corp will combine their electric vehicle platforms in an effort to slash prices down to levels comparable to conventional gasoline cars, the Nikkei newspaper said. The strategy comes as auto giants Volkswagen AG and Toyota Motor Corp are also aiming to mass-produce battery electric vehicles amid tightening emissions and fuel-economy regulations around the world. Franco-Japanese alliance partners Renault and Nissan have been among the most vocal proponents of the zero-emission technology but have struggled to lower costs enough as they developed their electric cars separately. The Nikkei said Renault and Japan's Mitsubishi Motors Corp , which recently came under Nissan's control, will use the same vehicle platform as Nissan's remodelled Leaf electric car expected to go on sale around 2018. The three companies will share key components such as the motor, inverter and battery, a move that would lower the Leaf's price by about a fifth, the paper said, without citing its sources. REUTERS SDR 0426