We use the engine to keep the car moving, and the brakes to slow down and stop the car. That’s the way it works, right?
Yes… but it isn’t quite that simple. You see, the key word here is “stopping.” Brakes are for stopping the car. Yes, they help slow the car down too, but your engine has more to do with that than you might think.
A couple of days ago, Angelo has discussed why coasting is bad. A commenter even noted that “you lose 80% of stopping power when you disengage gears.” I’m not entirely sure about the exact figures, but you can test the concept the next time you get in your vehicle.
How? Just take your foot off the accelerator.
Once you ease off the gas, the engine starts slowing down – and this reduction in speed transfers all the way down the transmission and to your tires. Basically, while you’re in gear and your foot is off the gas, your engine works to slow down your vehicle. In some cases, you can shift down one or two gears to slow down even further.
Why would you want to do this?
The most important reason is that you want your brakes to stop your car. By keeping your foot off your brakes, or by only pressing on them lightly, you prevent them from heating up. This prevents brake fade, making them more effective when you’re in a situation where you need to stop or slow down quickly.
Another reason, one related to this, is to keep your vehicle in control. If, for example, you were going downhill, your vehicle will accelerate as you move forward. By shifting down, you let your engine limit your acceleration – keeping your speed in check. Yes, you can also use your footbrake, but that brings us back to our first reason.
Basically, the point is this: use your engine to control your vehicle’s movement. The engine is for moving the car – both speeding it up and slowing it down. Your brakes are there to help slow it down, but their main purpose is for stopping.