The hydrogen storage properties of the alloys Ml-Ca-Ni (Ml: La-riched mischmetal) was systematically investigated. The experimental results show that the alloys Ml-Ca-Ni have good hydrogen storage capacity and hydriding/dehydriding kinetics. It was also found that the hydrogen storage capacity of Ml0.8Ca0.2Ni5 is more than 180ml/g. An automobile hydrogen storage tank used Ml0.8Ca0.2Ni5 hydride with hydrogen capacity of 20 Nm3 was designed and manufacted . The comparison test results reveal that with hydrogen-gasoline hybrid as its fuel, an gasoline engine may save gasoline by more than 30% and its thermal efficiency increases by more than 10%. Moreover, in its exhaust gases, the CO level decreases by 70% and the contents of HC and NOx also reduce. A demonstration test of a bus was carried out.