Any thing that is manufactured has the potential of a defective part, but there is no defective design in the i3 that would prevent you from making that trip safely. Just be aware that each time you stop, whatever your state of charge is, is the maximum the car will try to maintain when you start it up again, and if you are using energy faster than the REx can provide...you need to (most likely) slow down, or figure out why and fix it. Otherwise, you could keep going forever when refilling the fuel tank. It's not uncommon in the USA for the dealer to arrange it to be trucked to you when the distance is that great, but the whole franchise for selling the i3 is different in the UK than in the USA.