Vehicle emissions and fuel consumption are significantly affected by driving behavior. Many studies of eco-driving technology such as eco-driving training, driving simulator and on-board eco-driving device have reported potential reductions in emissions and fuel consumption. Use of on-board safety devices is mainly for safety, but also affects the vehicle emission and fuel consumption. In this study, an on-board safety device was installed to alert the driver and improve the driving behavior. A portable emissions measurement system (PEMS) was used to measure vehicle exhaust concentrations, including hydrocarbon (HC), carbon monoxide (CO), carbon dioxide (CO2) and nitrogen oxides (NOx). The driving parameters including vehicle speed, acceleration and position were also recorded. A specific test route was designated for the experiment to cover both urban and highway conditions. The driving parameters and emissions data were compared before and after the installation of the on-board safety device with the same driver. The vehicle specific power (VSP) methodology was applied to evaluate the effects of the on-board safety device on driving behavior. The results indicated that the device had a positive effect on the driver’s driving behavior. The percentage of time spent in excess speeding and strong acceleration decreased from 22.2% to 14.7%. As a result, an average reduction of 19% in fuel consumption was observed. In addition, HC, CO, CO2 and NOx emissions showed a reduction of 54%, 27%, 18% and 3% respectively. However, the time spent on idling showed no change with the installation of the device.