曾因车厢顶部背着硕大气包而被人们视为落后象征的天然气汽车,再度受到了世界各国的青睐。目前全世界约有天然气汽车100万辆。使用以压缩天然气为燃料的汽车迄今已有60多年的历史,最早是在意大利投入运行的。近年来,燃油汽车特别是燃柴油的大型货车,给环境带来了严重的污染。法国国家运输安全研究所提供这样一组数字:一辆年行驶5万公里的15吨大卡车,每年排出一氧化碳177公 Natural gas vehicles that were regarded as a symbol of backwardness due to the huge air bag on the top of the compartment were once again favored by all countries in the world. There are about 1 million natural gas vehicles in the world at present. The use of CNG-fueled vehicles has been in existence for over 60 years and was first put into operation in Italy. In recent years, large-scale trucks, especially diesel-fueled trucks, have brought serious pollution to the environment. The French National Institute of Transport Safety provides a set of figures for a 15-tonne truck traveling 50,000 kilometers a year and 177 grams of carbon monoxide annually