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The impact of cars on environment and climate

Why you should learn about the environment

The whole world is trying to reduce its carbon dioxide emissions. A significant part of those emissions is caused by vehicle traffic. This means that the Riksdag, the government and its agencies have an interest in getting people to be as environmentally friendly as possible.

Environmental objectives in the curriculum for a category B licence

  • Be aware of the environmental requirements set for the vehicles.
  • Learn the correlation between driving style and environmental impact (eco-driving).
  • Understand how your choice to drive (rather than take the train, for example) impacts on the environment.

Greenhouse effect

The greenhouse effect is named after the function of a greenhouse. The rays of the sun come in through the glass ceiling of the greenhouse and give off heat. Most of that heat then remains in the greenhouse, creating a suitable environment for the plants.

The same process occurs naturally at a larger scale as well. In that case, the earth is the plant and the atmosphere is the glass ceiling.

The problem arises when the greenhouse effect is unnaturally enhanced. This is what happens when we extract fossil fuels from the earth and burn them. One of the residues that form is carbon dioxide (the most important greenhouse gas).

The carbon dioxide rises and gets caught in the atmosphere, which makes the “glass ceiling” thicker, making it trap too much heat.

Normal greenhouse effect

Normal greenhouse effect
The rays of the sun (yellow arrows) pass through the atmosphere (grey line) and reach the earth. Much of the heat is absorbed (red dots) and the excess bounces off the earth’s surface and is reflected back out into space (red arrows).

Enhanced greenhouse effect

Enhanced greenhouse effect
The car releases emissions into the atmosphere, which makes it thicker. When the atmosphere gets thicker, some of the heat rays reflected back from the surface cannot get through. These rays instead bounce back towards the earth while emitting more heat. In other words, the earth is getting warmer than it otherwise would.


There are many potential consequences of a warmer climate.

Examples of climate change consequences

  • Natural disasters – meltwater from giant glaciers can cause great floods.
  • Agricultural disturbances – certain food crops are highly sensitive to temperature shifts, which means that very small changes can make their cultivation impossible.
  • Diseases – we can get diseases spreading to Sweden that currently cannot withstand our cold climate.
  • Water shortage – a large part of the earth’s population uses glacier meltwater as drinking water. If the glaciers melt, these people will have no water to drink.

Equipment & technology

Catalytic converter

  • The catalytic converter transforms the harmful substances in petrol into carbon dioxide and water.
  • 80–95% of the harmful substances are eliminated.
  • The catalytic converter has an operating temperature of 400–600°C, which means that it takes a while for it to function optimally.

Engine heater

The engine heater is located underneath the bonnet and is used to warm up the engine. There are many benefits to an engine heater:

  • The catalytic converter starts working sooner.
  • Lower fuel consumption.
  • Less wear on the engine.

How long the engine heater should be turned on:

  • +10 °C = 20 minutes before leaving.
  • 0 °C = 60 minutes (1 hour) before leaving.
  • -20 °C = 90 minutes (1.5 hours) before leaving.
Car with caravan.

It is not only the weight of the caravan that increases the fuel consumption. The additional air resistance also plays a part.

Keeping the engine heater on for too long is unnecessary and bad (as it uses up electricity without any benefit).

Reduce air resistance

Walking around in a storm with a large open parasol in front of you is hard. The same is true for the car. The fewer wind-catching areas there are, the less fuel is needed to propel the car. Things to consider when it comes to air resistance:

  • Take off rails and roof boxes when not in use.
  • Avoid large spoilers etc. (The aerodynamic benefits are often negligible on regular cars).
  • Drive with the windows shut. An open side window or sunroof disrupts the airflow around the car, which leads to greater air resistance.
  • Avoid tyres that are too wide.

Correct tyre pressure

A steel marble will roll better than a deflated football. The same is true when it comes to the tyres of the car. Tyres with high air pressure will roll more easily than tyres with less air in them. The more easily the car rolls, the less fuel it takes to propel it. It also reduces the wear on the tyres.

10–15% over the tyre pressure indicated in the manual is usually best. Read more about tyre pressure in the section on tyres.

Use the air conditioning sparingly

The air conditioning (AC) uses a lot of energy. If you turn off the AC, you can save 5–10% in fuel consumption.

Wash the car correctly

You should wash your car in a location intended for that purpose, such as a petrol station. These places have special floor drains that collect any harmful residues from the wash.

Waxing your car not only makes it look good – the wax also forms a protective film which means that less dirt sticks to the car. This in turn means fewer washes are necessary, which is good for the environment.

Chemical emissions

Carbon dioxide (CO2)

Carbon monoxide (CO)

  • Impairs the oxygen uptake in the blood.
  • Leads to tiredness and can be life-threatening in large amounts.
  • Catalytic converters reduce carbon monoxide emissions.

Hydrocarbons (HC)

  • Causes cancer.
  • May impact on genetic material.
  • Contributes to the formation of tropospheric ozone.

Nitric oxide (NOx)

  • Contributes to the acidification of soil and eutrophication of lakes.
  • Impacts on human genetic material and airways.
  • Contributes to the formation of tropospheric ozone.

Tropospheric ozone

  • Ozone that forms too close to the ground is harmful to plants and animals.


  • Eutrophication is when a lake gets too many plant nutrients (similar to us eating greasy fast food every day).
  • This leads to harmful algal blooms and the lakes getting overgrown.
  • The greatest causes are nitric oxide from traffic and phosphorus.


  • Acidification is when acid substances spread to an abnormally large extent.
  • Causes damage to lakes and forests.
  • The greatest causes are nitric oxide from traffic and phosphorus.

Soot and harmful particles

  • Common problem in cities with many cars.
  • Affects the airways and can cause cancer.


  • Disturbing car noise is a common occurrence in cities.
  • Noise protection reduces the problems.

Theory test with video questions

Video questions – Swedish theory test Free demo – try the questions