Resistance to advancement is the force that prevents a vehicle from moving at a constant speed. It directly affects performance, from the speed it reaches to fuel consumption, cornering grip and braking distance.
The engine moves the wheels through the transmission, but there are different factors that generate this resistance to the forward movement of your car. Let’s analyze them briefly:
Rolling resistance
Rolling resistance is the resistance produced by the deformation of the tyre when driving in a straight line on a flat surface. It also offers resistance due to the deformation of the terrain on which it is driven. It is also known as rolling friction.
He rolling resistance coefficient It takes into account various variables: from the speed at which you are travelling to the weight of the vehicle, including the grip of the surface or characteristics of the wheel such as its radius, material and pressure.
Can it be avoided? No, but it can be reduced.
- Choose a type of tire with low rolling resistance, which minimizes the effect when driving on asphalt (very common in electric cars). However, they will not have as good a grip on curves as other conventional ones.
- It is also vital to have the correct tyre pressure. Under-inflation increases rolling resistance and, while over-inflation reduces this, it also causes less grip for the tyre as it has less contact surface with the ground and the rubber lasts less as it does not wear evenly.
- Another aspect to keep an eye on is the condition of the wheels. Some time ago we made a guide to know when to change tires.
Mechanical friction resistance
Mechanical friction resistance is caused by engine and transmission parts.
Can it be avoided? No, but it can be reduced:
- It is vital that the engine has a correct lubrication at all times. You must know how to measure the oil level and act accordingly if it falls below the minimum level.
Aerodynamic drag
Aerodynamic drag is the force exerted by the air – in the opposite direction – when your car is moving. It is not fixed: it depends on the size and external shape of the vehicle, the speed at which it is travelling, the density of the air and also the direction and strength of the wind.
Can it be avoided? No, but it can be reduced:
- Choosing a low-riding car more aerodynamic shapes. Look at the drag coefficient of different car models (it ranges from 0.20 to 0.40, and varies greatly depending on the body of the car. Generally, the most square shapes (SUVs and minivans) are the most common. And, if you want to use little fuel, avoid pick-ups. Vehicles with an open cargo bed can have up to 30% more fuel consumption compared to those with a closed cargo bed.
- It is interesting to know how to drive a car in the wind. Especially when you suffer gusts of wind and drive high bodieswith greater lateral surface area.
Inertia resistance
Inertia is the property of a body – including cars – to remain in its state, whether at rest or in motion. When you travel at a certain speed and want to accelerate, the force generated by the engine must overcome the resistance of inertia.
Can it be avoided? No, but it can be reduced:
- Anticipation: To increase speed quickly you have to press the accelerator harder than when you are increasing speed more gradually. And the same thing happens when braking. By anticipating these situations whenever possible you will spend less, as we indicate in our tips for using less fuel.
Slope resistance
The gradient you encounter when driving your car uphill generates an opposing force that is directly proportional to the weight of the vehicle – including the load it is carrying – and the angle of the gradient.
Can it be avoided? No, but it can be reduced:
- When riding on steep slopes, make sure you shift into a suitable gear early enough to avoid stalling the engine, as we indicated in our tips for climbing and descending mountain passes. Avoid changing gears too frequently, unless the angle of the slope also varies.
