While there is extensive research on the technical potential of electric vehicles (EVs) to provide electricity system flexibility, no work has sought to understand how EV manufacturers see their role in this transition. Here we present an interview study with 11 EV manufacturers active in the UK, determining their perceptions on the market potential for demand-side flexibility using EVs. Findings indicate manufacturers view significant potential in this market, but believe time is needed (i.e. in the 2020s) for the EV market to develop before there is enough system/consumer demand for flexibility using EVs. They believe better price signals are needed, and prefer a consumer-led approach (rather than, for example, mandatory smart charging). Most manufacturers recognise they have a role in making flexibility a viable offering, but for it to succeed it needs coordination with other players, notably energy suppliers, aggregators, network operators and consumers. Governments should have a role in encouraging and brokering such partnerships. There was little evidence of concern that network constraints resulting from multiple EVs charging on the same circuit could act as a brake on sales. We identify a risk that EV growth could outpace available infrastructure and flexibility market mechanisms, leading to grid management challenges.