Most automakers tout their cars’ ability to go from 0 to 60 in X seconds flat. The Bugatti Veyron, for example, can hit 60 mph in 2.4 seconds, making it one of the fastest cars in the world. While all that torque, muscle, and power may be impressive to some, at Esurance we’re more concerned with a car’s ability to stop on a dime.
After all, when it comes to avoiding a car accident and staying safe on the road, it’s the stopping power that can make a difference between a near miss and an oh-no!
So what does stopping power depend on? And how long does it take to go from 60 to 0?
Stopping distance: how long it takes to go from 60 to 0
For the average car with reasonably good tires, here’s how it breaks down:
In normal driving conditions, it takes roughly 4.6 seconds — also the time needed to read or send a text — to stop safely. And that means if you’re texting while you drive (not good!), you could very easily collide with the car in front of you.
Add rain or snow to the mix and you need even more cushion because wet surfaces reduce friction, making it hard for your tires to grip and slow down.
The physics behind stopping distance
I’m not a physicist. But I happen to know someone with a master’s degree in mechanical engineering (who, coincidentally, now calculates risk as a homeowners actuary at Esurance).
According to Joe F., coming to a complete stop from 60 mph requires turning kinetic energy (or the energy of motion) into heat through friction. For a car, this involves brakes transmitting stopping force to your tires, which then grip to the road to slow you down until you come to dead halt. So, whether you drive a Bugatti or a Buick, the physics of deceleration is the same.
But coming to a full stop doesn’t just depend on the laws of physics. It also depends on your car’s brakes and tires. And, of course, the condition of the road and your ability to react play a role as well.
The 3-second rule: Is it unsafe?
Given that it takes more than 4 seconds to stop safely at highway speeds, does following the 3-second rule actually put you at risk? It would seem so.
To be safe, AAA recommends that you give yourself a cushion of 4 or more seconds when driving at freeway speeds. Of course, when the roads are slick with rain or slushy with snow, give yourself a cushion of 6 or more seconds.