The IOA is pleased to see the Department for Transport DfT considering measures to tackle excessively noisy vehicles and consulting on potentially introducing an exhaust noise test into the MOT. In responding to their consultation Changes to the date of the first MOT test and Research into other MOT enhancements, we have advised on a number of points. These include that data from trials of measuring exhaust noise in an MOT centre should be compared to equivalent data recorded in a quiet free-field environment. This will enable the impact of background sound and reflecting surfaces on the measured levels to be understood. In addition, although the loud part of the test only lasts a few seconds, it is acknowledged that neighbourhood disturbance could be an issue in some situations, especially if such tests are undertaken outside.
Issues that could reduce the impact a noise test in the MOT might have on reducing excessive vehicle noise are also highlighted. For example, loud exhaust systems could be removed beforeIOA Response the MOT and replaced after the test. In addition, there is little correlation between exhaust noise levels and the noise levels recorded in tests designed to be more representative of real world driving and typical exposure to traffic noise. Any such test would have to consider how to address modern exhaust systems and electric cars with added sound, where the amount of noise they make is often linked to software defining the mode the vehicle is in. Also, a number of factors would need to be considered when deciding on an appropriate limit value for passing or failing the MOT.
Consultation: Changes to the date of the first MOT test and Research into other MOT enhancements
