????盡管現在新的鉆探技術和新探明石油貯量使油價和最高產量問題面臨的壓力有所減輕，但對替代燃料汽車的需求仍然在增長。環境問題和政府管制已經使尋找傳統汽油內燃機的替代品成為汽車廠商和消費者的當務之急。聯邦政府要求，到2025年平均每加侖英里數應達到54.5英里——這對傳統技術來說是一個極其具有挑戰性的目標。加州則已經開始要求增加零排放汽車或插電式混合動力車的數量。

????但是應該朝哪個方向努力呢？考慮到諸多因素，如使用習慣、效率和成本等，能替代汽油的東西有十幾種，比如電力、天然氣、植物油，甚至還有太陽能。而正如汽車網站Edmunds.com的約翰?歐戴爾所指出的那樣，就算天然氣這樣最有希望的替代品，它的推廣也受到同一件事的阻礙：加油或充電基礎設施的匱乏。

????考慮到這一點，我們來看看一些現有替代品的情況，以及關于它們未來應用的嘗試性預測。

????While new drilling technologies and oil reserves are taking the pressure off gasoline prices and peak production issues, demand for alternative fuel vehicles continues to grow. Environmental concerns and government regulations have made finding substitutes for the conventional gasoline-powered internal combustion engine a priority for both manufacturers and consumers. The federal government is demanding an average of 54.5 miles per gallon by 2025 -- a challenging target for traditional technologies. California is requiring increasing numbers of zero-emission or plug-in hybrid cars.

????But what direction to go? Depending on considerations like usage patterns, efficiency, and cost, there are at least a dozen substitutes for gasoline as motor fuel, including electricity, natural gas, vegetable oil, and even sunlight.

????Even the most promising ones like natural gas, as John O'Dell of Edmunds.com points out, are handicapped by the same thing: a lack of infrastructure for refueling or recharging.

????With that in mind, here's a look at the alternatives that are available today, along with some tentative predictions about their prospects for the future.

????1. 油電混動

????本田Insight和豐田普銳斯（Prius）是第一代混動車，它們都是1999年在美國上市的，而今天在售的混動車已經有40種。部分使用電能驅動汽車在燃油經濟性和排放上都有很大好處。油電混合動力車用電池在低速行駛時供能，或控制啟停。這種電池通過再生制動或內燃機充電，無須插電。雖然豐田廣受歡迎的普銳斯一直是最暢銷的混動車（它2013年的總銷量將超過20萬輛），但現在法拉利（Ferrari）和保時捷（Porsche）也開始推出超級混動車了，比如保時捷帕納梅拉S混動車搭載了一臺3.0升的V6引擎，但續航能力仍能達到城市路況每加侖22英里，高速公路每加侖30英里。

????1. Gas-electric hybrids

????The first hybrid models, the Honda Insight and Toyota Prius (above) both reached the U.S. in 1999, and today some 40 gas-electric models are for sale. Using electricity to partially power vehicles has significant fuel economy and emissions benefits. Gas-electric hybrids use a battery to provide power at low speeds, or to handle stop/start. The battery is charged through regenerative braking and by the internal combustion engine, and it need not be plugged in. While Toyota's (TM) popular Prius remains the best-selling hybrid -- more than 200,000 will be sold in 2013 -- their numbers now include supercars made by Ferrari and Porsche. The Porsche Panamera S hybrid has a 3.0 liter V6 engine and still gets 22 mpg city/30 mpg highway.