<p>This study investigates whether self-reported aberrant driving behaviours, measured through the Driver Behaviour Questionnaire (DBQ), are reflected in objectively observed speed behaviour under real urban driving conditions, and whether these relationships vary across road contexts. An instrumented-vehicle experiment was conducted with 45 Portuguese drivers on a controlled urban circuit in Coimbra, including repeated observations across road segments and roundabouts. Drivers were characterised according to three DBQ dimensions: infractions and aggressive driving (IAD), non-intentional errors (NIE), and lapses. Mean speed, speed variability, and acceleration/deceleration profiles were analysed using random-parameter linear regression models to account for repeated observations and inter-driver heterogeneity. Results show a consistent positive association between IAD and higher mean speed, as well as stronger acceleration and deceleration patterns across both road segments and roundabouts. In contrast, NIE is associated with lower speeds and lower acceleration/deceleration levels. Lapses show limited and inconsistent effects. Importantly, the magnitude and stability of these associations vary across road elements, with more complex environments such as roundabouts amplifying behavioural differences in speed variability and manoeuvre execution. These findings provide empirical support for the ecological validity of DBQ-based behavioural profiling while demonstrating that its expression is context-dependent. Risky driving behaviour should therefore be understood as the result of an interaction between driver disposition and infrastructure characteristics, rather than as a fixed individual characteristic.</p>