Many times, when debuting cars to journalists for press functions, companies will have about ten or twenty cars on-hand. Usually, these cars all carry English (or whatever country it is being debuted in) licence plates. Since the cars are all registered at the same time, they all carry the same digits on their licence plate. The "GTO" series is just a chance thing that Mitsubishi happened to get for their press ceremony (though you can pay for special plates, and if it's under six characters and English, they probably did).