要弄清楼主的疑问,首先要清楚这句话的句子结构,这句话主语是the next car,谓语部分是did not take,宾语是him into the downtown areas of paris 做的是状语,去的地点.其中有两个定语从句,the boy stopped 是一个定语从句,修饰的是前面的car,由于引导词which/that在定从中作宾语可以省略,所以stopped后面是省略了引导词,当然stopped就是一个过去式了.as he hoped it would.也是一个定语从句修饰前面的downtown areas,as当正如讲时引导定语从句.而在这个从句中又包含了一个宾语从句it would,做hope的宾语,后面省略了：take him to the downtown aera
所以这句话完整的可以是
the next car (which) the boy stopped did not take him into the downtown areas of paris as he hoped it would（take him to the downtown aera）.
句意：
男孩拦下的下一辆车没有把他带到他所希望的巴黎城郊地区去.