Why do people drive under the speed limit?

Slow drivers can be infuriating. You see, the problem with being a motorist is that you can’t communicate with those around you (well, you can, but it mostly involves flashing your high beams).  As a motorist, you can only make assumptions about other people’s intentions and their motives. You can only make guesses about why they’re driving under the speed limit or why they’re tailgating you.

Unfortunately, in the heat of the moment, when tensions are rising, we often arrive at the conclusion that they are being ignorant or intentionally trying to annoy us. In the real world, we can speak to one another and apologize. We can explain the situation and help to diffuse it. In the world of motoring, communication is severely limited.

There are a number of possible reasons why people will drive below the speed limit. Knowing these reasons can significantly help with road rage (or increase it, depending on the reason).

Mechanical issues

Sometimes, a motorist will experience mechanical issues with their vehicle. In some cases, this can happen mid-drive. i.e. They hear an unfamiliar sound emanating from their engine and they instinctively slow down in order to minimize the damage. Example: You’re mid-drive and the timing belt in your car begins to squeal. Some engines, upon detecting a mechanical issue, will automatically reduce the amount of power that is being given to the engine. This is to minimize the possibility of further damage.


Newer drivers and elderly drivers can experience anxiety while driving. Learner drivers will feel anxious about travelling at high speeds, simply because they lack experience. Elderly drivers, on the other hand, can feel anxious if their reaction speed, hearing and eyesight has deteriorated over the years. The onset of mental conditions such as dementia, Parkinson’s Disease and Alzheimer’s Disease can also lead to reduced cognition and confusion.

The driver may also be experiencing anxiety because of a previous road collision or accident.


In some cases, the driver in question may be transporting a fragile piece of cargo. For example, the slow-moving van driver in front of you could be carrying a grandfather clock or a window pane. He or she could be worried about the possibility of hitting bumps or pot holes at a high speed. They could also be worried about the possibility of heavy equipment moving around.


Lets face it: Highway hypnosis is common and lone motorists can easily slip into a daydream.
In this particular scenario, they might not be aware of the fact that they are driving 10 km/h under the speed limit. They could be thinking about their stressful day or they could have “zoned out” while listening to the radio.


If the motorist is carrying a passenger, they may be distracted by a conversation that they are having. In this case, they’re not paying same amount of attention to their speedometer that a lone driver would. In some cases, the conversation could be heated (an argument between a couple, for example).


A lot of motorists will instinctively slow down if they are talking on the phone or attempting to check a text message. This practice is commonplace, despite the fact that using a phone while driving is illegal in many countries. If this is the case, then you have every right to be annoyed.
Not only are they putting other motorists at risk, they’re also holding you up with their slow driving.

However, for your own safety, you should maintain some distance and avoid tailgating.

Engine limitations

Simply put: Smaller / older cars can be slow and sluggish. They are slower to take off and they can struggle at higher speeds. For example: A friend of mine was telling me about a work van that he had to transport from one garage to the next. The van was old and he told me that he struggled to get it up to the speed limit. To make matters worse – If traffic slowed or came to a stop, the vehicle would take a while to recover its speed.

Saving money on gas / petrol

Certain cars have certain “sweet spots” and ardent savers are quick to realize that they can save money on fuel by driving at a certain speed. In many cases, this “sweet spot” falls below the speed limit.

For example: Many freight / transport companies will add speed limiters to their trucks, simply because they know that higher speeds can lead to higher diesel costs. While reading up on this topic in the past, I’ve come across examples where driving 1 mile per hour under the speed limit led to savings of about $10 dollars per week (or roughly $1 dollar per hour). Obviously, all vehicles are different and there are other factors at play. Still, there is a significant amount of evidence to suggest that lower speeds are advantageous if you are worried about the costs of fuel consumption.

Adverse weather conditions

Motorists will slow down if they perceive what they think are adverse weather conditions.
Note how I used the word “perceive” there, as different motorists will have different opinions about what constitutes an adverse weather condition. For example: If you drive in Ireland, then you will probably be used to rain and wet road conditions. However, a visitor from a drier climate might drop their speed to 20-30km/h under the speed limit.

Winds will also effect vehicles differently, depending on their size and shape. Although you might not feel the crosswinds as much, the motorist in front of you might feel as though they’re about to be launched into orbit.

Sunday drivers

Sunday drivers are motorists that aren’t going anywhere in a hurry. They’re either calm by nature or they’re not too worried about arriving on time. These kind of motorists are quick to point out that everyone needs to “calm down” and “stop rushing”.

Poor visibility

One evening, my window washer fluid ran out just as I had taken off. It was night time and my visibility wasn’t as great as it should have been. Although I didn’t drive under the speed limit, I certainly didn’t go heavy on the accelerator. It’s easy to imagine other drivers coming across similar issues, especially if they have a malfunctioning demister or dirt and grim has built up on the inside of their windshield.

Bad eyesight

Unfortunately, there are a sizeable amount of people that will drive without their glasses. There are also a sizeable amount people who should have glasses, but don’t. This issue becomes worse at night, when visibility is low. Often, you will see these motorists driving 20 or 30 under the speed limit, frantically turning on their high beams as they struggle to navigate some of the darker roads.

Unfamiliar surroundings

When people are driving on an unfamiliar road, they have a tendency to slow down. This is because they are unsure about what is up ahead. This is particularly true for smaller winding roads. The situation is made worse when the motorist in question is actively looking for a place or a specific turn-off. If you have ever found yourself in a position where you are looking for a particular area, then you probably noticed how you had a tendency to slow down at times.

This article was posted in Opinion.