The acceleration force refers to the vehicle’s resistance to speed variations. This force holds you back when you increase your speed and also moves you forward when you slow down. In other words, it means that you consume energy to accelerate up to a certain speed but can recover part of that energy when you decelerate, allowing you to drive a certain distance without consuming fuel.
The main factors influencing the acceleration force are:
The acceleration magnitude
The acceleration magnitude is the difference between the initial speed and the arrival speed. For example, the difference between 0 km/h to 50 km/h or between 50 km/h and 70 km/h.
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As with the aerodynamic force, the energy required to accelerate is exponentially proportional to its magnitude. For example, when you double the acceleration magnitude by going from 0 to 60 km/h versus 0 to 30 km/h, the acceleration force quadruples.
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The vehicle mass
This mass depends on the type of vehicle and the load carried.
| How to reduce the acceleration force? |
Here are the main things you can do to better control the acceleration force and, thus, your fuel consumption.
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Eliminate accelerations
Eliminating accelerations presents potential fuel savings of 100%. It reduces the need to brake and, thus, the need to accelerate. After an initial acceleration, it’s best to adjust your driving so you don’t have to slow down or stop.
There are three driving techniques that can help you eliminate accelerations:
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Anticipation more
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- In the city, try to look ahead to the next two or three traffic lights so you can adjust your speed and catch them when they are green.
- On roads you usually take, be aware of patterns at traffic lights and areas where you are more likely to have to stop for traffic.
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Anticipating more means being better able to predict slowdowns and stops so you can react better from energy-efficiency and safety standpoints. The goal is to reduce unexpected braking by being more aware of the road. |
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Increase the distance between vehicles
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Keeping a safe distance between you and the vehicle ahead of you gives you enough time to react so you don’t have to break suddenly if the flow of traffic changes.
- A simple way to assess a safe distance is to count 3 to 6 seconds between you and the vehicle ahead of you.
- Use the space created to safely change lanes and take your foot off the gas pedal during momentary slowdowns.
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Try to maintain a constant speed
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- In the city, maintain your speed by slightly varying the pressure applied to the gas pedal versus repeatedly stepping on and off the gas pedal.
- On the highway, if you’re driving at a speed of 90 km/h, avoid oscillating between 80 and 100 km/h.
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Try to maintain a constant speed by limiting speed variations as a result of using your gas or brake pedal. The goal is to stabilize your speed in function of the road context. This is also achieved when you anticipate more and maintain a safe distance between you and the vehicle ahead of you. |
The route you take is also important to maximizing opportunities for eliminating accelerations. For example, taking a route with two known traffic lights is better than taking one with several required stops.
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Reduce accelerations
| Reducing accelerations represents potential fuel savings of over 25%. This means limiting the upper range of your acceleration speed. For example, accelerating from 0 to 50 km/h consumes 30% more energy than accelerating from 0 to 60 km/h. Why keep accelerating when you’re getting ready to stop anyway? Once again, you have to anticipate more so you can better predict stops and slowdowns and, thus, slow down in time. |
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- If you’re between two required stops that are relatively close together, accelerate from 0 to 45 km/h instead of from 0 to 50 km/h.
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Recover accelerations
Recovering accelerations represents potential fuel savings of over 50%. This means using the energy accumulated during the acceleration to slowly decelerate without having to brake over a long stretch of road, using the momentum of your vehicle to coast for free – not unlike coasting on a bicycle without having to pedal.
- When you approach a red traffic light, take your foot off the gas pedal well in advance so you can slowly come to a stop while reducing the use of your brakes.
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While this is difficult to do in traffic, many realistic recovery levels can be achieved to generate fuel savings. Take your foot off the gas pedal sooner and let your vehicle decelerate on its own instead of using the brakes. Once again, you will have to anticipate more traffic stops and slowdowns to start the recovery process sooner. |
Now let’s see how the effects of eliminating, reducing and recovering accelerations by comparing a traditional driver (in black) with an eco-driver (in green). In this example, the driver must go from point A to point B on a road where he will encounter one traffic light and one required stop.
Traditional driver (black line)
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Eco-driver (green dotted line) |
| 1. Accelerates up to the legal speed limit, for example, 50 km/h in the city. |
1. Looks ahead, anticipates, and sees the red traffic light. |
| 2. Drives. The light is red. |
2. Reduces acceleration by adopting a speed that will allow him to get to the light after it turns green. |
| 3. He must stop. |
3. Drives and gets to the light, which is green. While putting his foot over the brake in case he has to stop, he sweeps the intersection and cautiously crosses it without having to stop. He has eliminated the need to come to a full stop and the need to re-accelerate. |
| 4. Waits until the light changes. |
4. Looks ahead, anticipates, and sees the required stop. |
| 5. Accelerates to 50 km/h. |
5. Accelerates to 45 km/h versus 50 km/h. |
| 6. Drives. |
6. Drives. |
| 7. Brakes at the required stop. |
7. Takes his foot off the gas pedal and lets his car coast to the stop. The required driving force is nil, as he is recovering the kinetic energy of his vehicle. |
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8. Slowly brakes and brings his vehicle to a stop. |
You can also save gas this way during traffic slowdowns.
| Traditional driver (black line) |
Eco-driver (green dotted line) |
| 1. Drives at an adequate speed. |
1. Looks ahead, anticipates, and predicts the slowdown. He increases the distance between him and the vehicle ahead of him. |
| 2. He notices that the flow of traffic ahead of him isn’t moving as fast. He maintains his speed and reaches the flow of traffic. |
2. Slowly takes his foot off the gas pedal so as to adjust his speed to that of the vehicles in front of him. He recovers. |
| 3. Steps on the brakes to adjust his speed to that of the vehicles ahead of him. |
3. The distance between his vehicle and the vehicle in front of him serves as a cushion, giving him the space and the time he needs to easily adjust his speed. |
| 4. When the traffic becomes fluid, he accelerates again until he reaches the desired speed. |
4. The group of vehicles has had time to go through the area requiring a slowdown and he picks up his speed. |
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5. Once the slowdown has passed, he goes back to maintaining a comfortable distance between his vehicle and the vehicle in front of him and picks up his speed. |
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Selecting a vehicle that fits your true needs allows you to reduce the mass of your vehicle and your fuel consumption.
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Removing unnecessary items from your trunk or storage rack will reduce the total mass of your vehicle and your fuel consumption.
Source : Virage simulation, modèle de consommation de carburant, results not published
