(8)Directive 2003/37/EC in a first stage limited the mandatory application of the EC whole-vehicle type-approval procedure to the vehicle categories T1, T2 and T3 and did not provide for all requirements necessary in order to apply for EC whole-vehicle type-approval on a voluntary basis for other categories. In order to complete the internal market and to ensure that it functions properly, this Regulation should allow manufacturers to apply for EU whole-vehicle type-approval for all categories covered by this Regulation on a voluntary basis, thereby enabling them to benefit from the advantages of the internal market by means of the EU type-approval.