There is a host of existing technologies that could radically improve the internal combustion engines that power our cars. 

    有许多现有的技术可以很好地提高我们汽车的内燃机引擎效率。
 
    Tuning Up Car Engines

    In the U.S. alone, our cars' tailpipes spew some 1.2 billion metric tons of carbon dioxide per year. This is a big part of why our global climate is changing. But there are a lot of ways to cut back on that pollution—without switching to alternative fuels or electric cars.

    That's because internal combustion engines, despite a century of tinkering, have a lot of room for improvement in efficiently converting gasoline to power.

    For instance, simply changing the action of intake and exhaust valves in a car while it is running could significantly improve gas mileage. And that's technology that exists today.

    Simple changes in our driving could help too. Turning off the engine when idling, making sure tires are properly inflated, coasting to red lights rather than slamming on the brakes and slowly accelerating from a stop—all can boost fuel efficiency as evidenced by hypermilers, those who have mastered the art of traveling hundreds of miles on a few gallons of gas.

    Ultimately, hybrid vehicles and electric cars—whether powered by batteries or fuel cells—will deliver even more environmental rewards. But until they are widely available, simple changes to the internal combustion engine—and the way we drive—could as much as double gas mileage.

    调整汽车引擎，提高燃烧效率
 
    仅仅在美国，我们的汽车每年排放的二氧化碳就大概有12亿吨。这很大一部分可以解释为什么全球正经历气候变暖。但是也有很多的方法来减少这种污染——而且不需要改为使用可替代燃料的汽车或者电动车。
 
    这是因为尽管一个世纪以来，人们对内燃机引擎一直在改造，不过在把汽油有效地转化为动力方面，它仍然还有很多的提升空间。

    比如，在汽车行驶过程中，仅仅改变进气阀和出气阀的历程就能显著地提高汽油里程。而且这种技术目前就有。
 
    简单的改变我们的驾驶习惯也能起到提高燃料效率的作用。在等待的时候关掉引擎、确保轮胎充气适宜、遇到红灯的时候，以滑行的方式而不是以猛然刹车的方式停下来、启动的时候缓慢加速——这些方式都能提高燃料效率，而且也被“超级里程者”们证实过。“超级里程者”就是那些仅用几加仑汽油就能行驶好几百英里的人。

    最终混合动力汽车和电动汽车——不管它们是靠蓄电池驱动还是靠燃料电池驱动——将带来更加好的环境效果。但是，在这些汽车还没有广泛使用之前，对内燃机简单的改变以及我们驾驶方式的改变能使汽油里程加倍。

Vocabulary:

A host of：大量；许多
Radically：根本地；（美口语）很好的
Internal combustion engine：内燃机引擎
Tailpipe：尾气管
Spew：喷
Billion：十亿
Metric：米制的；公制的
Alternative：替代的
Tinker：小修补；小修理
Convert：转化
Gasoline“：汽油
Valve：阀门
Mileage：英里里程
Inflate：充气
Coast：滑行
Slam：砰地关上；用力推
Accelerate: 加速
Boost: 提高
Ultimately:最终地
Hybrid vehicle: 混合动力汽车