Safety has also come into question as some of the lithium-ion batteries -- widely believed to be the key to making viable electric cars -- have shown a tendency to overheat and sometimes catch fire.

• 电动车的安全性也受到质疑，被普遍视为电动轿车商业化要害部件的锂离子电池有时可能出现过热甚至起火的现象。