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

    有許多現(xiàn)有的技術可以很好地提高我們汽車的內燃機引擎效率。
 
    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.

    調整汽車引擎，提高燃燒效率
 
    僅僅在美國，我們的汽車每年排放的二氧化碳就大概有12億噸。這很大一部分可以解釋為什么全球正經歷氣候變暖。但是也有很多的方法來減少這種污染——而且不需要改為使用可替代燃料的汽車或者電動車。
 
    這是因為盡管一個世紀以來，人們對內燃機引擎一直在改造，不過在把汽油有效地轉化為動力方面，它仍然還有很多的提升空間。

    比如，在汽車行駛過程中，僅僅改變進氣閥和出氣閥的歷程就能顯著地提高汽油里程。而且這種技術目前就有。
 
    簡單的改變我們的駕駛習慣也能起到提高燃料效率的作用。在等待的時候關掉引擎、確保輪胎充氣適宜、遇到紅燈的時候，以滑行的方式而不是以猛然剎車的方式停下來、啟動的時候緩慢加速——這些方式都能提高燃料效率，而且也被“超級里程者”們證實過。“超級里程者”就是那些僅用幾加侖汽油就能行駛好幾百英里的人。

    最終混合動力汽車和電動汽車——不管它們是靠蓄電池驅動還是靠燃料電池驅動——將帶來更加好的環(huán)境效果。但是，在這些汽車還沒有廣泛使用之前，對內燃機簡單的改變以及我們駕駛方式的改變能使汽油里程加倍。

Vocabulary:

A host of：大量；許多
Radically：根本地；（美口語）很好的
Internal combustion engine：內燃機引擎
Tailpipe：尾氣管
Spew：噴
Billion：十億
Metric：米制的；公制的
Alternative：替代的
Tinker：小修補；小修理
Convert：轉化
Gasoline“：汽油
Valve：閥門
Mileage：英里里程
Inflate：充氣
Coast：滑行
Slam：砰地關上；用力推
Accelerate: 加速
Boost: 提高
Ultimately:最終地
Hybrid vehicle: 混合動力汽車