Following distance — New Jersey Permit Test
Following distance on the New Jersey permit test — 6 rules, each with the reason behind it and a question on it while it is fresh.
The rules
The common rule of thumb is one car length, about 20 feet, of following distance for each 10 mph of speed.
It scales with speed because stopping distance does. At fifty that is five car lengths.
the rule of thumb most often used is to keep one car length back (about 20 feet) for each 10 miles per hour of speed
Tailgating is following too closely behind the vehicle directly in front, and it is a common cause of crashes.
Close behind, you inherit whatever the driver ahead does, with no time to do anything else.
Tailgating refers to following too closely behind a vehicle directly in front.
Under the three-seconds-plus rule a driver should take at least three seconds to reach the object the car ahead just passed.
Counting works at any speed, which is why it beats trying to judge a distance in feet.
If it takes at least three seconds before your vehicle passes the object, a motorist should have enough distance for a sudden stop.
In bad weather the following interval should be increased to four or more seconds.
Wet road means longer stops, so the gap in front has to grow with it.
During bad weather, the time interval should be increased to four or more seconds.
Stopping distance is perception distance plus reaction distance plus braking distance.
Two of the three happen before the brake is touched, which is why a gap matters more than good brakes.
Stopping distance = Perception Distance + Reaction Distance + Braking Distance.
On ice at 20 mph the minimum safe following distance is 12 car lengths.
Ice stretches a two-length gap into twelve. Nothing about the car feels different until you brake.
Ice 12 car lengths
On the test
How much following distance does the car-length rule of thumb give?
1 car length for each 10 mph. It scales with speed because stopping distance does. At fifty that is five car lengths. New Jersey Driver Manual, p.94: “the rule of thumb most often used is to keep one car length back (about 20 feet) for each 10 miles per hour of speed”
How this works
Most practice tests hand you a bank of questions and leave the manual somewhere else. This one puts them together.
You read one law and the reason behind it, then answer a question on that law while it is still fresh. Get it right and you move on; get it wrong and you have found the gap while it is cheap to fix, not on the morning of the exam.
Learning one rule at a time, and proving it immediately, is what turns a manual you skimmed into something you actually know — and it makes studying feel like getting somewhere rather than like waiting to find out.
What it costs
- One payment, once — not a subscription. Nothing renews and there is nothing to cancel, for an exam you sit one time.
- Free to start: a 10-question test and the first section of cards. No sign-up and no account.
- Paying opens the rest of the cards, unlimited full-length practice tests, and retests built from exactly the questions you got wrong.
- Every level up to Prepared — 3 tests passed in a row.
- Do the work, fail the real exam, and we refund you.
Where these come from
Every rule here is checked against New Jersey Driver Manual, published by the New Jersey Motor Vehicle Commission, and against the state code itself. Last checked 2026-09-15.