If the luggage of the people transported in your vehicle does not fit in the trunk of the same and you have no choice but to carry it on the roof rack, how do you think . that the suitcases should be placed to achieve greater security and save fuel ? .
Well attached and on edge, that is, resting on its smaller surface or narrower side .
Well supported and lying down, that is, resting on its largest surface or widest side .
Their position is indifferent, the important thing is that they are well supported .