2009 GMC Acadia Owner's Manual - Page 265

Driving Your Vehicle 4-13 Hill and Mountain Roads Driving on steep hills or through mountains is different than driving on flat or rolling terrain. Tips for driving in these conditions include: { CAUTION Coasting downhill in N (Neutral) or with the ignition off is dangerous. The brakes will have to do all the work of slowing down and they could get so hot that they would not work well. You would then have poor braking or even none going down a hill. You could crash. Always have the engine running and the vehicle in gear when going downhill. Winter Driving Driving on Snow or Ice Drive carefully when there is snow or ice between the tires and the road, creating less traction or grip. Wet ice can occur at about 32°F (0°C) when freezing rain begins to fall, resulting in even less traction. Avoid driving on wet ice or in freezing rain until roads can be treated with salt or sand. Drive with caution, whatever the condition. Accelerate gently so traction is not lost. Accelerating too quickly causes the wheels to spin and makes the surface under the tires slick, so there is even less traction. Try not to break the fragile traction. If you accelerate too fast, the drive wheels will spin and polish the surface under the tires even more. • Keep the vehicle serviced and in good shape. • Check all fluid levels and brakes, tires, cooling system, and transmission. • Going down steep or long hills, shift to a lower gear. { CAUTION If you do not shift down, the brakes could get so hot that they would not work well. You would then have poor braking or even none going down a hill. You could crash. Shift down to let the engine assist the brakes on a steep downhill slope. • Stay in your own lane. Do not swing wide or cut across the center of the road. Drive at speeds that let you stay in your own lane. • Top of hills: Be alert - something could be in your lane (stalled car, accident). • Pay attention to special road signs (falling rocks area, winding roads, long grades, passing or no-passing zones) and take appropriate action.