Abstract: A vehicle monitoring device 10 consists of a damped-pendulum transducer 12 coupled to a potentiometer 14. The analog output of the potentiometer 14, following a braking test with the vehicle concerned, is sampled in a peak/trough detector 16. A microprocessor 18 comprising signal processing unit 20 and arithmetic unit 22 controls the sampling and sums, averages and displays the output of microprocessor 18 on a digital display 24. If desired, a suitably programmed small computer may be used in place of microprocessor 18. According to one aspect of the invention, the device 10 is adapted to serve as a brake-efficiency meter. In this case, the display 24 will be arranged to display the average, or currently-measured, deceleration, as the case may be. In an alternative application, the device 10 is adapted to serve as a safe-slope meter.