2009 BMW 3 Series Owner's Manual - Page 120

Things to remember when driving for a short period after the engine is switched off. Hydroplaning When driving on wet or slushy roads, reduce road speed. If you do not, a wedge of water can form between tires and road surface. This situation, known as hydroplaning, means that the tire can completely lose contact with the road surface, so that neither the car can be steered nor the brake be properly applied.< The risk of hydroplaning increases with declining tread depth on the tires, refer also to Minimum tread depth on page 215. other road users. The heat generated in this process helps dry the pads and rotors to ensure that full braking efficiency will then be available when you need it. Hills To prevent overheating and the resulting reduced efficiency of the brake system, drive long or steep downhill gradients in the gear in which the least braking is required. Even light but consistent brake pressure can lead to high temperatures, brake wear and possibly even brake failure.< You can increase the engine's braking effect by shifting down, all the way to first gear if necessary. This strategy helps you avoid placing excessive loads on the brake system. Downshifting in manual mode of the automatic transmission, refer to page 57. Never drive with the clutch held down, with the transmission in neutral or with the engine switched off; otherwise, engine braking action will not be present or there will be no power assistance to the brakes or steering. Never allow floor mats, carpets or any other objects to protrude into the area around the pedals; otherwise, pedal function could be impaired.< Driving through water Drive through water on the road only if it is not deeper than 1 ft/30 cm, and then only at walking speed at the most. Otherwise, the vehicle's engine, the electrical systems and the transmission may be damaged.< Use the parking brake on inclines On inclines, do not hold the vehicle for a lengthy period using the clutch; use the parking brake instead. Otherwise, greater clutch wear will result.< For more information about the drive-off assistant, refer to page 84. Corrosion on brake rotors When the vehicle is driven only occasionally, during extended periods when the vehicle is not used at all, and in operating conditions where brake applications are less frequent, there is an increased tendency for corrosion to form on rotors, while contaminants accumulate on the brake pads. This occurs because the minimum pressure which must be exerted by the pads during brake applications to clean the rotors is not reached. Should corrosion form on the brake rotors, the brakes will tend to respond with a pulsating effect that even extended application will fail to cure. Braking safely Your BMW is equipped with ABS as a standard feature. Applying the brakes fully is the most effective way of braking in situations in which this is necessary. Since the vehicle maintains steering responsiveness, you can still avoid possible obstacles with a minimum of steering effort. Pulsation of the brake pedal, combined with sounds from the hydraulic circuits, indicate that ABS is in its active mode. Driving in wet conditions When roads are wet or there is heavy rain, briefly exert gentle pressure on the brake pedal every few miles. Monitor traffic conditions to ensure that this maneuver does not endanger 118 Online Edition for Part no. 01 41 2 603 048 - © 08/09 BMW AG