A mobility scooter is a major assistive technology that replaces human ambulatory functions for people with disabilities. A license is often not required for driving a mobility scooter; therefore, less skilled drivers might create safety concerns. An effective way of reducing these safety risks is by assessing the driving skills of users. The existing assessment measures mostly score the task performance using manual observations. In this study, we have developed a novel assessment system that logs the driving operations by using add-on sensors. This system can monitor the operations of a mobility scooter including the angles of the throttle lever and the steering tiller. The subjects were seven older adults who participated in the driving test involving six tasks; the driver performances were video recorded, and the vehicle operation data were logged. The video analysis showed that two subjects crashed their scooters into objects or made contact with objects during the test course. To extract the characteristic patterns of the operations from the logs, 2D histograms of the operational status durations were investigated for each subject and task. Subsequent analysis of the operation logs identified the two subjects who had crashed their vehicles during the test drive. Our results proved that the driving operation logs could be used complementarily as a simple and low-cost tool for assessing a person's driving skills.