As Marcus says, if you have a genuine need that the vehicle is no longer suitable, then you can terminate early. This may incur a fee of between £0 – £250, and you forfeit any good condition bonus on that car. If you early terminate 3 times i believe they then question if the scheme is right for you, e.g you may be refused an early termination on the 4th request. Early termination can be requested at any point – heard it being done just a couple of month in to a new lease before, not that uncommon.