General
The overall grade is normally derived from the average of the nine individual grades. Adjustments to the weighting of the individual grades can be made.
The guidelines described below for determining individual grades (definition) and the listed grading scales are the default settings.
Standing time with engine running
The grade is calculated from the ratio of standing time with the engine running to the engine running time.
Standing time with the engine running is only considered standing time after 60 seconds. (Time can be adjusted; note the grade key)
Definition
- Motor running time = speed > 300 rpm
- Standing time with engine running = speed < 2 km/h AND speed > 300 rpm
Cause of standing time with engine running
The engine runs while the vehicle is stationary so that the air conditioning can cool down.
Measures
Switch off the engine during longer periods of inactivity, such as at level crossings or when visiting customers.
Grade key
Ratio of engine running time when stationary to total engine running time:
| Grade | Percent |
|---|---|
| 1 | < 2% |
| 2 | 2% - 4% |
| 3 | 4% - 6% |
| 4 | 6% - 8% |
| 5 | 8% - 10% |
| 6 | > 10% |
Engine speed above limit
The grade is obtained from the ratio of the time the engine speed is over the limit and the driving time.
Engine speed over limit does not apply in coasting mode.
Definition
- Engine speed over limit = revolutions > 1600 rpm
- Coasting mode = Instantaneous consumption < 3 l/h AND Speed > 2 km/h
Measures
- Avoid engine speeds above 1600 rpm
- At 1300 rpm, approximately 95 percent of the power is available. (Source: Mercedes Benz)
Grade key
Ratio of engine speed above limit to total driving time:
| Grade | Percent |
|---|---|
| 1 | < 2% |
| 2 | 2% - 4% |
| 3 | 4% - 6% |
| 4 | 6% - 8% |
| 5 | 8% - 10% |
| 6 | > 10% |
Avoidable stops
The grade is calculated based on the ratio of avoidable stops to total stops.
An avoidable stop lasts less than 60 seconds.
After a stop, you must drive faster than 10 km/h. Only then will the test continue.
Definition
Avoidable stop = When the following criteria were fulfilled 15 seconds before the stop
- The brake was applied for more than 4.5 seconds (30%) over a period of 15 seconds.
- The current consumption is more than 3 l/h during the 15 seconds (slow rolling to a stop is acceptable).
Stop = speed < 2 km/h AND speed > 50 rpm
Measures
- Approach potential stops with foresight.
- Let the vehicle roll.
- In traffic jams, follow the vehicle in front of you without stress.
Grade key
Ratio of avoidable stops to all stops:
| Grade | Percent |
|---|---|
| 1 | < 30% |
| 2 | 30% - 40% |
| 3 | 40% - 50% |
| 4 | 50% - 60% |
| 5 | 60% - 70% |
| 6 | > 70% |
Predictive driving
The grade is calculated from the ratio of the duration of speed losses with the main brake to the total duration of speed losses.
Definition
- Duration of the losses of speed using the main brake = speed drops by more than 10 km/h AND main brake is active.
- Total duration of speed loss = speed drops by more than 10 km/h.
Measures
- Foot off the accelerator earlier.
- Use retarder instead of main brake.
Grade key
Ratio of the duration of speed reduction with main brake to the total duration of speed reduction:
| Grade | Percent |
|---|---|
| 1 | < 2% |
| 2 | 2% - 4% |
| 3 | 4% - 6% |
| 4 | 6% - 8% |
| 5 | 8% - 10% |
| 6 | > 10% |
Driving time with cruise control
The grade is calculated based on the ratio of driving time with cruise control above the cruise control limit to the total driving time above the cruise control limit.
Calculation
Definition
Cruise control limit = 60 km/h
Grade key
Ratio of time driven with cruise control above 60 km/h to total driving time above 60 km/h:
| Grade | Percent |
|---|---|
| 1 | > 70% |
| 2 | 70% - 65% |
| 3 | 65% - 60% |
| 4 | 60% - 55% |
| 5 | 55% - 50% |
| 6 | < 50% |
Speed over the limit
The grade is calculated based on the ratio of the duration of speeding to the total driving time.
Exceeding the speed limit does not apply in thrust mode.
Definition
Speed over the limit = speed > 85 km/h
Measures
Do not drive faster than 85 km/h. (Fuel consumption increases by up to 3 litres per 100 kilometres between 80 and 90 km/h.)
Grade key
Ratio of time above the speed limit to total speed:
| Grade | Percent |
|---|---|
| 1 | < 2% |
| 2 | 2% - 4% |
| 3 | 4% - 6% |
| 4 | 6% - 8% |
| 5 | 8% - 10% |
| 6 | > 10% |
Sharp braking
The grade is calculated based on the ratio of braking time during sharp braking to the total braking time.
Negative acceleration (also known as deceleration) occurs when the general formula
Definition
- Sharp braking = braking deceleration < -2 m/s²
- Braking = brake applied AND speed > 2 km/h
Example
A truck is travelling towards a construction site at a speed of 90 km/h. Five seconds later, its speed is only 80 km/h. Calculate the acceleration.
Since the calculated value is less than 0, this is a deceleration, a negative acceleration.
Measures
Avoid sharp braking with the service brake.
Grade key
Ratio of sharp braking time to total braking time:
| Grade | Percent |
|---|---|
| 1 | < 2% |
| 2 | 2% - 4% |
| 3 | 4% - 6% |
| 4 | 6% - 8% |
| 5 | 8% - 10% |
| 6 | > 10% |
Braking distance
The grade is calculated based on the ratio of braking distance to total distance.
Definition
- Braking distance = distance travelled with service brakes
- Total distance = Total distance travelled
Measures
Use the retarder instead of the service brake for braking.
Grade key
Ratio of distance travelled using the service brake to total distance travelled:
| Grade | Percent |
|---|---|
| 1 | < 1% |
| 2 | 1% - 2% |
| 3 | 2% - 3% |
| 4 | 3% - 4% |
| 5 | 4% - 5% |
| 6 | > 5% |
Coasting mode
The grade is calculated based on the ratio of the distance travelled using coasting mode to the distance travelled without cruise control engaged.
(This is not taken into account when cruise control is active.)
Definition
Coasting mode = Instantaneous consumption < 3 l/h AND Speed > 2 km/h
Measures
In coasting mode, the truck consumes hardly any fuel. Therefore, use coasting mode as often as possible.
(The term coasting describes the automatic function in motor vehicles that switches off the engine and disconnects it from the drive train while driving.)
Grade key
Ratio of kilometres travelled in coasting mode to total kilometres without cruise control engaged:
| Grade | Percent |
|---|---|
| 1 | > 21% |
| 2 | 21% - 16% |
| 3 | 16% - 11% |
| 4 | 11% - 7% |
| 5 | 7% - 4% |
| 6 | < 4% |