压缩天然气 (Compressed natural gas, CNG) 是一种燃料用天然气，作为石油替代能源，它是环保清洁燃料中比其他燃料泄漏时中安全得多的选项 （天然气比空气轻）。一般通过压缩天然气（主要是甲烷（CH₄））将体积压为标准大气压下的1%。存储在2900–3600 psi的圆柱或球形压力容器中。

只要改装为双燃料汽车（汽油／CNG） 的传统汽油内燃机汽车都可以使用天然气，相比之下比其他能源更兼容于现有设备。天然气汽车越来越多地用于在亚太地区、拉丁美洲、欧洲和美国的汽油价格上涨后。 作为高燃料价格和环境问题的回应，开始大量出现CNG改装套件和卡车、游览车和校车、火车等普及面。

Compressed natural gas (CNG) (methane stored at high pressure) can be used in place of gasoline (petrol), Diesel fuel and propane/LPG. CNG combustion produces fewer undesirable gases than the fuels mentioned above. It is safer than other fuels in the event of a spill, because natural gas is lighter than air and disperses quickly when released. CNG may be found above oil deposits, or may be collected from landfills or wastewater treatment plants where it is known as biogas.