Computer game technology was used for rapid prototyping of a sound based interface encouraging truck drivers to drive energy efficiently. The design process was inspired by user-centred agile methods. Interior sounds were made interactive by actively controlling them based on speed, engine speed, torque and acceleration. User feedback was collected at an early stage through contextual enquiry sessions during simulated driving. Based on the feedback the sounds were adjusted and effects on driver behaviour were measured in a simulator experiment. The effects on driver behaviour were small and not statistically significant (p>.05). However, assessments of preference and informativeness showed statistically significant differences between the design concepts (p<.05). The qualitative part of the study showed that the use of game technology for enabling assessment of interactive sounds in early design phases was useful and allowed for getting users into the loop early on. The framework was found to be suitable for designing interactive sounds, and the data collected provides insight into driver responses to using active noise control as a means for providing information to the driver.