????2. 插電式混動

????插電式混動車也叫PHEV，它與油電混動車類似，但電池容量更大，能光靠電能推動車行駛一定距離，也因此實現了零排放。這種電池隨后能插在電源上充電。容量更大的電池成本也隨之水漲船高——比如插電式普銳斯在最近降價前就需要多花7,000美元——而且目前美國在售的PHEV只有四種。通用汽車（General Motors）那款大名鼎鼎的增程式雪佛蘭沃藍達（Volt）每月銷量也不足2,000輛。

????2. Plug-in hybrids

????Plug-in hybrids or PHEVS are similar to gas-electric hybrids but have larger batteries that can propel the car limited distances on electricity alone, thus generating zero emissions. The batteries can then be recharged by being plugged into an electric power source. The cost of the larger batteries carries a hefty price premium -- an additional $7,000 for the plug-in version of the Prius before a recent price cut -- and only four PHEV models are currently available in the U.S. Sales of the best-known model, General Motors' (GM,Fortune 500) range-assisted Chevrolet Volt (above), have been running at less than 2,000 a month.