????各大汽車制造商及駕車者長期以來一直希望在燃油效率問題上得到一個簡單的解決辦法。曾經有一段時間，這個愿望看起來有可能實現。2009年，《財富》雜志（Fortune）撰文稱，由于電動汽車、混合動力汽車及柴油車等技術性的進展，“傳統的汽油內燃機似乎可以肯定地說正在日漸式微。”

????事實是，一種顛覆標準發動機、而且可負擔得起的技術尚未出現。行業預測機構LMC汽車咨詢公司（LMC-Automotive）預測，到2020年，98％以上的車輛將仍然使用某種形式的內燃機。LMC動力總成行業分析師麥克?奧莫托索稱，在2020年銷售的新車當中，約有72％的新車將只使用汽油，相比今天的84％僅下降幾個百分點。（其余大部分是混合動力車、柴油車或乙醇動力車。）

????鑒于在未來幾年內還不會出現革命性的突破，從大眾（Volkswagen）到寶馬（BMW），各大汽車制造商現在正尋找利用現有技術的新方法。鑒于美國燃油經濟性標準即將提高——到2025年將達到54.5 英里／加侖（mpg），上述措施正變得格外重要。（美國是世界上第二大汽車市場，僅次于中國。）為了達到新的燃油經濟性標準，各大汽車公司目前正在整合一系列現有技術，以期在已有120年歷史的內燃機的基礎上節約使用任何可能的點滴燃油。

????問及正在大量整合進入標準發動機的各種不同技術時，美國汽車工程師協會（Society of Automotive Engineers）的安德魯?斯馬特這樣說道：“展望2025年時，預計不會出現“銀子彈”——即能夠寄予厚望的新技術，但會出現大量“銀彈片”——即會出現大量技術性改進。”

????舉例而言，福特汽車公司（Ford）在新推出的、已成為市場熱點的EcoBoost發動機上就采用了技術性改進這個方法。福特在四年前推出了EcoBoost發動機，目前各款EcoBoost發動機汽車的銷量已超過350,000輛。EcoBoost發動機在傳統汽油發動機的基礎上進一步匯集了燃油缸內直噴、渦輪增壓及可變氣門正時等存在已久的技術。其中沒有多少是新技術，但匯集在一起，這些遞增式的改進與以往的傳統汽油發動機相比，在燃油經濟性方面實現了20％的提高。（點擊此處，了解更多有關EcoBoost的資訊。）

????他們是如何做到這點的呢？首先，EcoBoost重量輕。福特計劃明年在美國推出的1.0升三缸EcoBoost發動機將成為這家汽車制造商有史以來最小的發動機。其中發動機重量的減輕一部分是通過在發動機結構中使用鋁合金、而不是鑄鐵實現的。而且發動機的尺寸也較小，這要歸功于其他一些調整，使得它在縮小尺寸的同時、仍能保證強勁的動力輸出。

????這款發動機的尺寸順應了潮流。在整個汽車行業里，各大汽車制造商都已把六缸發動機換成四缸發動機。豪華汽車也是如此，對于豪華汽車而言，發動機小于八缸曾經被視為大不敬。現在，甚至連寶馬都加入這個潮流。公司將于明年開始銷售一款配有小型三缸發動機的汽車。

????汽車制造商有幾個辦法可以使小型發動機實現高性能。一個辦法是燃油缸內直噴。這項技術已經存在有一段時間了，但最近才獲得美國制造商的廣泛采用。為了避免浪費汽油，發動機內的精密噴射器把燃油噴入氣缸中的一個確切位置。這樣，燃油就能夠更完全燃燒，而所需的確切燃油量及應該擊中的準確位置均由電腦來確定。此外，由于燃油沒有通過發動機的其他部件、而是直接噴入氣缸，因此噴入氣缸后燃油溫度較低。溫度較低意味著汽油與空氣混合后產生的油氣較為稠密，從而使更多的油氣能夠在壓縮水平較高的情況下在較小的空間里得到使用。最終的結果是輸出的動力更大。

????Auto manufacturers and drivers alike have long yearned for a simple solution to fuel efficiency. For a while, it looked possible. In 2009 Fortune wrote that, thanks to advances such as electric cars, hybrids and diesel vehicles, "It seems certain that the traditional gasoline internal-combustion engine is on the wane."

????Truth is, an affordable technology to upend the standard engine still has yet to materialize. Forecaster LMC-Automotive predicts that by 2020, more than 98% of vehicles will still incorporate an internal combustion engine of some kind. And some 72% of new car sales in 2020 will run on gasoline only, says LMC analyst Michael Omotoso, down just a few points from today's 84%. (Most of the rest are hybrids, diesel or ethanol-powered.)

????Absent a revolutionary breakthrough within the next few years, carmakers from Volkswagen to BMW are now finding new ways to work with what they have. That's becoming especially important with a looming hike in fuel economy standards in the U.S. to 54.5 miles per gallon by 2025. (America is the world's second largest car market, after China.) To meet the new standards, companies are combining an array of existing technologies to eke out every possible bit of fuel savings from the 120-year-old internal combustion engine.

????Asked about the disparate technologies being crammed into the standard engine, Society of Automotive Engineers's Andrew Smart puts it this way: "When you look at 2025, the expectation is there is no silver bullet, but there is plenty of silver shrapnel."

????Ford (F), for one, took this approach in its new, much talked-about EcoBoost engine, which was introduced four years ago and has already sold more than 350,000 models. The EcoBoost is a compilation of long-standing technologies like direct injection, turbocharging and variable valve timing. Not much in it is new, but all together, the incremental improvements achieve a 20% gain in efficiency over its predecessors. (For more on the EcoBoost,click here.)

????How'd they do it? For starters, the EcoBoost is light. The one-liter, 3-cylinder model it plans to release in the states next year will be the carmaker's smallest engine ever. Part of the weight loss is achieved by using aluminum instead of cast iron in the engine construction. It's also smaller, thanks to the other tweaks that allow it to downsize and still pack a punch.

????The engine's scale is in keeping with a trend. Throughout the industry, automakers have swapped V6s for four-cylinder engines. That applies to luxury cars, too, where once it was sacrilege to have anything smaller than a V8. Even BMW is joining in, with a tiny, three-cylinder engine slated to go on sale next year.

????There are a few ways carmakers get smaller engines to deliver high performance. One is direct injection. The technology has been around for a while, but it has recently gained traction with U.S. manufacturers. To avoid wasting gas, precision injectors within the engine shoot fuel into an exact location in the cylinder. That allows for a cleaner burn, with a computer determining the exact amount of fuel needed and the exact spot it should land. Also, because the fuel goes directly to the cylinder without passing through other parts of the engine, it's cooler once it gets there. The colder temperature means the gas is denser, allowing for more of it to be used in a smaller space at higher levels of compression. The end result is a bigger punch.