Generally speaking we would not expect any particular issues with having a deadlock fitted to your vehicle, although you may need to declare this to your insurer as a modification and should you choose to sell the vehicle in the future you may find that some potential buyers are put off by this addition. In terms of whether it is technically possible to fit a deadlock the only issue we can foresee is whether a deadlock can function sufficiently in a vehicle with five doors, but we would suggest consulting with a suitable specialist who will be able to advise.