D
句意:然而一些人指出了飞行车的缺点。 A.Moreover而且;B.Instead相反;C.Infact事实上;D.However然而
根据上一行:We would fly at 480 kilometres per hour, avoiding traff ic lights,busy roads and speeding tickets讲述的是飞行车的优点,而这句话中some peoplepoint to the disadvantages of flying cars提到的是它的缺点,因此两句话之间是转折的关系,故答案是D。