This report details the work and findings of the behavioural insights investigation undertaken as part of a wider project investigating the impact of making changes to the current MOT system in the UK. The overall aim of this work was to provide evidence on specific topics relating to possible changes to the current MOT for light vehicles to ensure that it is kept up to date with developing technologies and best practice. The focus of this behavioural insights work was to investigate both the behavioural and attitudinal response of motorists to changes to MOT scheduling, as well as to understand how motorists respond to vehicle malfunction warning indicators. A semi-systematic evidence review, a public survey of 499 vehicle owners from across the UK, and a series of four focus groups were conducted as part of this study. Findings drawn from across these research tasks suggest that any change to the current MOT system in the UK that reduces or delays the frequency of MOT testing would not be well-received by the majority of the public and likely have a negative impact on overall vehicle safety. If the MOT frequency was to be reduced, some claim they would take on more responsibility for checking and maintaining their vehicle. However, others admit that they would be unlikely to take on this responsibility, which suggests that they would accept that their vehicle would go unchecked between MOTs and potentially risking safety. This latter group presents an obvious concern and must be considered if any changes are to be made regarding the frequency of the MOT.