美國環保署目前正研議車輛的環保和節能認定標準，環保署期望這些標準將引導美國各州允許這類車輛在公路的高乘載車道（high occupancy vehicle）上行駛，即使只有一人乘載。
規劃該提議的用意是促進消費者購買有設計環保和使用安全能量的車輛，且符合「安全可靠彈性效率運輸公平法案──路人資產」（The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users）的要求。
該提案適用於8500磅以下的汽車、運動型越野車（休旅車）、廂型車和卡車。如果要免受高乘載道的限制，這些車輛必須達到低排放量和節能的特殊規定。
美國環保署建議低排放的標準在於，車輛要符合「聯邦機動車尾氣排放標準」第一階段第五級或更佳層級，或者相同嚴格的加州LEV II級標準。節能標準則在於這些車輛與使用汽油燃料車輛相比，必須全面使用其他類燃料，或者混用燃料達到50%或更多市內燃料節約，或25%以上城市及高速公路燃料節約。
The U.S. Environmental Protection Agency, EPA, is proposing criteria for certifying vehicles as clean and energy efficient. The agency intends the criteria to guide states that choose to allow such vehicles on high occupancy vehicle, HOV, lanes – even when the vehicles have only one occupant.
The proposal, which was required by The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users, SAFETEA-LU, is designed to spur the purchase and use of vehicles that are better for the environment and energy security.
The proposal applies to cars, SUVs, vans and trucks below 8,500 pounds. To be eligible for the HOV exemption, these vehicles would be required to meet specifications for both low emissions and energy-efficiency.
To be considered low emission, EPA proposes that a vehicle would have to be certified to either the stringent federal Tier 2 bin 5 standard or cleaner or the equally stringent California LEV II standards.
To be considered energy efficient, EPA proposes that a vehicle would have to be either a dedicated alternative fuel vehicle, or a hybrid vehicle achieving 50 percent or better in-city fuel economy or 25 percent or better in combined city/highway fuel economy compared to a similar gasoline fuelled vehicle.
全文及圖片詳見 ENS報導
