Just to quantify this, the shortest 60-0 stopping distance for a "consumer-grade" car (meaning not a formula one vehicle) is the Porsche 911, which can do it in 27m. This is nearly 6 vehicle lengths. Usual safety guidelines are to stay about 3 car lengths behind whoever you're following, so even world's greatest brakes are not gonna save you if the vehicle in front stops in 0m because it hits an immovable pile of already stopped objects itself.
3 car lengths seems way too close to be following at highways speeds. Assuming a car is about 16 ft long, that gives you less than half a second of reaction time at 70 mph. Even at 25 mph, it's still less than 1.5 seconds.
I very much prefer to be 3 SECONDS behind the person in front of me. It's a nice metric that works at basically all speeds above 30.
According to the Utah government's Drivers Handbook[0] (printed page 27, or PDF page 36), they recommend a 2 second distance on clear dry roads:
following distance
Watch when the rear of the vehi-
cle ahead passes a sign, pole, or
any other fixed point. Count the
seconds it takes you to reach the
same point (one-thousand-one,
one-thousand-two.) You are
following too close if you pass that point before counting
two seconds. Slow down and check your new following
interval. Repeat until you are following no closer than two
seconds.
Always increase your following distance on slick roads,
when following large vehicles, motorcycles, or vehicles
pulling a trailer, at night, in fog, in bad weather and when
following vehicles that stop at railroad crossings (transit
buses, school buses or vehicles carrying dangerous mate-
rial.)
> Usual safety guidelines are to stay about 3 car lengths behind whoever you're following
Uh, no. Usual safety guidelines are to stay a speed-dependent distance behind whomever you're following. The one I've heard most often quoted is one car length per ten miles per hour, so at 70mph you should be a minimum of seven car lengths behind.
Three lengths is comically short for those kinds of speeds.
