What distinguishes all GNR buses and at the same time frustrates the meticulous enthusiast is the fact that every single bus was different in some feature or appearance although they may have been from the same tranche. No two buses were identical they may have had different window openings sliding vent or droplite type. The seat moquette patterns were very often different, even in batches of the same type of vehicle constructed together. The company also had the habit or re-bodying vehicles frequently which whilst engendering increased interest for the enthusiast also led to some confusion among the same fraternity as to a vehicle's genesis. Fleet numbers were allocated in a straight numerical sequence and also included the lorry fleet, often changing to make way for batches of new vehicles, the highest number was allocated to a 1953 AEC Regent III number 442. The GNRI was numbered among the few Irish operators who ran double deckers.

The GNR supported its Road Motor Services from a network of important garages located in Dublin, Drogheda, Dundalk, Cavan, Armagh, Lurgan, Donegal, Ballyshannon, Keady and Belfast (Grosvenor Street).

The Hill of Howth Tramway was also technically a part of the Road Motor Services and it bequeathed some of its nomenclature. Bus drivers were always referred to as "Motormen" and buses known, as "cars" such was the charming nature of its operations.