It is widely assumed telematics will play a major part in helping make the road freight sector more sustainable. Telematics works at the interface of road vehicles and the road network, helping to ensure the former make the most efficient and rational use of the latter. The exact nature of this interaction is the topic of this paper. Four archetypal street patterns were modelled using traffic microsimulation, populated with vehicles possessing various levels of telematics, and run multiple times to reveal outcomes in terms of journey length, duration, cost and carbon emissions. The findings show that the topology of urban street patterns interacts strongly with the level of telematics and the route guidance it provides. In some network types the amount of route guidance provided led to consistent improvements in network and vehicle performance, whilst in other networks the same performance could be achieved with 100% telematics as it could with 0%. A fundamental relationship is revealed between the universal network coefficient Beta (β) and the overall level of telematics required to optimise performance across all variables. The implications for telematics strategies are profound: it seems that every driver does not need to know everything in order to bring about optimal network performance.