The posted speed limit is 55 mph, but there is heavy fog. Under the basic speed law, you should:

Drive slower than 55 mph, at a speed that is safe for the conditions

Drive at 55 mph, since that is the limit

Drive at least 45 mph to keep up with traffic

Turn on your high beams and keep your speed

In good conditions, what is the minimum following distance most state handbooks recommend?

One car length, whatever your speed

How do you check your following distance using the seconds rule?

Note when the vehicle ahead passes a fixed object, then count seconds until you reach it

Count the cars between you and the vehicle ahead

Look at your speedometer and divide by 10

Watch the brake lights of the vehicle ahead

You should increase your following distance when:

Following a motorcycle or driving on a wet road

Driving on a dry, straight road in daylight

A school zone sign reads SPEED LIMIT 20 WHEN CHILDREN ARE PRESENT. You must:

Obey the 20 mph limit whenever children are present or the conditions on the sign apply

Drive 20 mph at all times, day and night

Slow down only if a crossing guard signals you

Your car begins to hydroplane on a wet road. You should:

Ease off the gas, keep the wheel straight and avoid hard braking

Turn the wheel sharply toward the shoulder

A driver is tailgating you. What is the safest response?

Increase the space in front of you and let the tailgater pass when possible

Brake suddenly to warn the driver

Move onto the shoulder at full speed

Driving much slower than the flow of traffic on a freeway:

Can be dangerous and may be illegal if it blocks the normal flow of traffic

When following a large truck, you should:

Stay far enough back to see the truck's side mirrors

Follow closely to save fuel in its draft

Stay right behind it so the driver knows you are there

Pass it on the right whenever possible

At night, you should drive at a speed that lets you:

Stop within the distance lit by your headlights

Keep up with the fastest vehicle on the road

Stay at the posted limit at all times

In a highway work zone, speeding fines are:

Often doubled or increased, depending on the state

Total stopping distance is made up of:

Perception distance, reaction distance and braking distance

The length of your vehicle plus one car length

Posted speed limits are designed for:

Ideal conditions; you must slow down in rain, snow, fog or heavy traffic

Drivers with more than five years of experience

Speed Limit and Following Distance Questions, With Answers

Speed and following distance questions test whether you can choose a safe speed and a safe gap, not just recite a number. The key rules: never drive faster than conditions allow, even below the limit; keep at least 3 seconds behind the vehicle ahead in good conditions and more in bad ones; and remember that doubling your speed roughly quadruples your braking distance. Try the 15 questions below.

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The posted speed limit is 55 mph, but there is heavy fog. Under the basic speed law, you should: A. Drive at 55 mph, since that is the limit / B. Drive at least 45 mph to keep up with traffic / C. Drive slower than 55 mph, at a speed that is safe for the conditions / D. Turn on your high beams and keep your speed. Answer: C. Drive slower than 55 mph, at a speed that is safe for the conditions. Most states have a basic speed law: you may never drive faster than is safe for current conditions, even if you are under the posted limit. In fog, use low beams and slow down.
In good conditions, what is the minimum following distance most state handbooks recommend? A. 1 second / B. At least 3 seconds / C. One car length, whatever your speed / D. 10 feet. Answer: B. At least 3 seconds. Most handbooks recommend at least a 3-second gap in good conditions, and more in rain, at night, in heavy traffic or behind large vehicles. Some states recommend 4 seconds.
How do you check your following distance using the seconds rule? A. Count the cars between you and the vehicle ahead / B. Look at your speedometer and divide by 10 / C. Watch the brake lights of the vehicle ahead / D. Note when the vehicle ahead passes a fixed object, then count seconds until you reach it. Answer: D. Note when the vehicle ahead passes a fixed object, then count seconds until you reach it. Pick a sign, pole or shadow. When the rear of the vehicle ahead passes it, count “one-thousand-one, one-thousand-two…”. If you reach the object before you finish counting, you are too close.
You should increase your following distance when: A. Following a motorcycle or driving on a wet road / B. Driving on a dry, straight road in daylight / C. Traffic is light / D. You are in a hurry. Answer: A. Following a motorcycle or driving on a wet road. Leave extra space on wet, icy or gravel roads, at night, in bad weather, behind motorcycles (which can stop quickly) and large trucks, and when someone is tailgating you.
Unless another limit is posted, the speed limit in residential and business districts in many states is: A. 15 mph / B. 25 mph / C. 35 mph / D. 45 mph. Answer: B. 25 mph. Many states set 25 mph as the default limit in residential and business districts, but some use 30 mph or other values. Learn your state's default limits from its handbook.
A school zone sign reads SPEED LIMIT 20 WHEN CHILDREN ARE PRESENT. You must: A. Drive 20 mph at all times, day and night / B. Ignore it on weekends only / C. Obey the 20 mph limit whenever children are present or the conditions on the sign apply / D. Slow down only if a crossing guard signals you. Answer: C. Obey the 20 mph limit whenever children are present or the conditions on the sign apply. School zone limits apply during the times or conditions shown on the sign, such as when children are present or lights are flashing. School zone limits and fines vary by state.
Your car begins to hydroplane on a wet road. You should: A. Brake hard to stop quickly / B. Accelerate to regain traction / C. Turn the wheel sharply toward the shoulder / D. Ease off the gas, keep the wheel straight and avoid hard braking. Answer: D. Ease off the gas, keep the wheel straight and avoid hard braking. Hydroplaning happens when tires ride on a film of water. Ease off the accelerator, steer straight, and do not slam the brakes. The best prevention is slowing down in heavy rain and keeping good tires.
A driver is tailgating you. What is the safest response? A. Increase the space in front of you and let the tailgater pass when possible / B. Brake suddenly to warn the driver / C. Speed up to get away / D. Move onto the shoulder at full speed. Answer: A. Increase the space in front of you and let the tailgater pass when possible. Give yourself more room ahead so you can brake gently if needed, and change lanes or slow slightly to let the tailgater pass. Never brake suddenly to “teach a lesson”.
If you double your speed, your braking distance becomes about: A. The same / B. Twice as long / C. Three times as long / D. Four times as long. Answer: D. Four times as long. Braking distance grows with the square of speed. Going from 30 to 60 mph makes your braking distance about four times longer, before you even count reaction time.
Driving much slower than the flow of traffic on a freeway: A. Is always the safest choice / B. Can be dangerous and may be illegal if it blocks the normal flow of traffic / C. Is required in the left lane / D. Is allowed only on weekends. Answer: B. Can be dangerous and may be illegal if it blocks the normal flow of traffic. Many states prohibit driving so slowly that you impede normal traffic, and some freeways post minimum speeds. If you must go slower, stay in the right lane and use hazard lights if needed.
When following a large truck, you should: A. Follow closely to save fuel in its draft / B. Stay right behind it so the driver knows you are there / C. Stay far enough back to see the truck's side mirrors / D. Pass it on the right whenever possible. Answer: C. Stay far enough back to see the truck's side mirrors. Trucks have large blind spots, or No-Zones. If you cannot see the driver's face in the truck's side mirror, the driver cannot see you. Extra distance also lets you see the road ahead.
At night, you should drive at a speed that lets you: A. Stop within the distance lit by your headlights / B. Keep up with the fastest vehicle on the road / C. Use only your parking lights / D. Stay at the posted limit at all times. Answer: A. Stop within the distance lit by your headlights. If you cannot stop within the area your headlights light up, you are overdriving your headlights. Slow down, especially on dark rural roads.
In a highway work zone, speeding fines are: A. Never enforced / B. Often doubled or increased, depending on the state / C. Lower than usual / D. Enforced only at night. Answer: B. Often doubled or increased, depending on the state. Many states double or increase fines for speeding in work zones, especially when workers are present. Obey the posted work zone limit and watch for flaggers.
Total stopping distance is made up of: A. Braking distance only / B. Reaction distance only / C. Perception distance, reaction distance and braking distance / D. The length of your vehicle plus one car length. Answer: C. Perception distance, reaction distance and braking distance. Stopping distance includes the distance you travel while noticing a hazard, the distance while moving your foot to the brake, and the distance while the brakes slow the car.
Posted speed limits are designed for: A. Any weather and traffic / B. Nighttime driving only / C. Drivers with more than five years of experience / D. Ideal conditions; you must slow down in rain, snow, fog or heavy traffic. Answer: D. Ideal conditions; you must slow down in rain, snow, fog or heavy traffic. Speed limits assume good weather, light traffic and a dry road. When conditions are worse, the safe and legal speed is lower than the posted limit.

What speed and distance questions cover on the DMV test

This topic mixes numbers with judgment. Some questions ask for a figure from your handbook — a default residential limit, a school zone limit, how many seconds of following distance — and others describe a scene, such as fog, a tailgater or a slow truck, and ask what a safe driver does. Default limits vary by state, so your own handbook decides the exact numbers.

Speeding is a factor in a large share of U.S. traffic deaths, according to NHTSA, which is why examiners keep coming back to it. The answer they want is almost always the one that leaves you more time and space to react.

The rules behind the most-missed questions

These principles answer most speed and following distance questions:

Basic speed law: in most states you may never drive faster than is safe for conditions, even below the limit. A driver going 55 in fog can be ticketed in a 55 zone.
3-second rule: at least 3 seconds in good conditions; add time in rain, at night, behind motorcycles and trucks, and when tailgated.
Speed and stopping: braking distance grows with the square of speed, so doubling speed roughly quadruples braking distance.
Advisory vs. legal speed: yellow speed plaques are recommendations; white SPEED LIMIT signs are the law.
Too slow can be wrong too: impeding traffic is illegal in many states. Keep right if you drive slower.
Large vehicles: commercial drivers are trained to keep at least one second for every 10 feet of vehicle length, plus one more second above 40 mph. Do not cut in close in front of a truck.

When to add following distance
Condition	Why
Wet, icy or gravel roads	Tires grip less; stopping takes longer
Night or poor visibility	You see hazards later
Behind a motorcycle	It can stop faster than a car
Behind a large truck	It blocks your view of the road ahead
Being tailgated	You need room to brake gently

How to study speed and following distance

Write down the default limits from your state handbook (residential, business, school zone, rural highway, interstate), because those numbers are the ones most likely to show up. Our speed limits and following distance guide explains the rules behind them.

Then practice the seconds rule as a passenger: pick fixed objects and count. Finish with topic practice tests and a full mock exam, and review the safe driving questions, which cover weather and night driving in more depth.

Speed and following distance FAQ

What is the 3-second rule?

It is the recommended minimum gap behind the vehicle ahead in good conditions. When its rear passes a fixed object, you should be able to count three seconds before you reach the same object.

What is the basic speed law?

Found in most states' vehicle codes, it says you may never drive faster than is reasonable and safe for weather, traffic, visibility and road conditions, even if you are under the posted limit.

Are speed limits the same in every state?

No. Each state sets its own default and maximum limits. Residential limits are often 25 mph, and rural interstate limits typically range from about 65 to 75 mph, with a few states posting higher.

How much following distance do I need in rain or snow?

More than in good conditions. Many handbooks suggest at least doubling your gap on wet roads and leaving much more on snow or ice.

Can I get a ticket for driving too slowly?

Yes, in many states, if you impede the normal flow of traffic or drive below a posted minimum speed without a safety reason.