| 1.6.2. | For vehicles in which the energy is absorbed by the braking action of the engine alone, a tolerance of ±5 km/h on the average speed shall be permitted, and the gear enabling the speed to be stabilized at the value closest to 30 km/h on the 6 per cent down-gradient shall be engaged. If the performance of the braking action of the engine alone is determined by a measurement of deceleration, it shall be sufficient if the mean deceleration measured is at least 0.5 m/s2. | a0c0 |