2003 Chevrolet Impala Owner's Manual - Page 219

Braking Braking action involves perception time and reaction time. First, you have to decide to push on the brake pedal. That's perception time. Then you have to bring up your foot and do it. That's reaction time. Average reaction time is about 3/4 of a second. But that's only an average. It might be less with one driver and as long as two or three seconds or more with another. Age, physical condition, alertness, coordination and eyesight all play a part. So do alcohol, drugs and frustration. But even in 3/4 of a second, a vehicle moving at 60 mph (100 km/h) travels 66 feet (20 m). That could be a lot of distance in an emergency, so keeping enough space between your vehicle and others is important. And, of course, actual stopping distances vary greatly with the surface of the road (whether it's pavement or gravel); the condition of the road (wet, dry, icy); tire tread; the condition of your brakes; the weight of the vehicle and the amount of brake force applied. Avoid needless heavy braking. Some people drive in spurts - heavy acceleration followed by heavy braking - rather than keeping pace with traffic. This is a mistake. Your brakes may not have time to cool between hard stops. Your brakes will wear out much faster if you do a lot of heavy braking. If you keep pace 4-6 with the traffic and allow realistic following distances, you will eliminate a lot of unnecessary braking. That means better braking and longer brake life. If your engine ever stops while you're driving, brake normally but don't pump your brakes. If you do, the pedal may get harder to push down. If your engine stops, you will still have some power brake assist. But you will use it when you brake. Once the power assist is used up, it may take longer to stop and the brake pedal will be harder to push. Anti-lock Brake System (ABS) Your vehicle may have anti-lock brakes. ABS is an advanced electronic braking system that will help prevent a braking skid. If your vehicle has anti-lock brakes, this warning light on the instrument panelwill come on briefly when you start your vehicle. When you start your engine, or when you begin to drive away, your anti-lock brake system will check itself. You may hear a momentary motor or clicking noise while this test is going on, and you may even notice that your brake pedal moves or pulses a little, This is normal.