As a rule of thumb, the more aggressive the adjustments, the more likely the driver will notice an impact on the driving experience. This is important because drivers (and especially employees) tend to respond to changes in a known acceleration rate by pressing the accelerator pedal further or accelerating for longer—which in turn chews into the original mileage gains.
The key for employees and other non-owner drivers (delivery drivers, for example) is to maximize the adjustments without creating a noticeable change in the driving experience. For most commercial vehicles, trucks, and even many passenger vehicles, this is mode 3 or 4. We don’t recommend going beyond mode 4 for non-owner drivers.
If you do decide that you want to experiment with more aggressive modes, one of the best methods is to work up the ladder starting at Mode 1. Allow drivers to acclimatize in this mode for two weeks before bumping to the next mode. Then repeat this process until you reach your target mode. This process makes the overall large change less noticeable by dividing it into smaller adjustments distributed over many weeks.
For owner drivers, we recommend driving in mode 3 for one or two weeks initially. Thereafter, you can go to a higher mode as long as you remain aware of the human tendency to compensate through more use of the accelerator pedal. If you find the latter happening, dial back the mode a notch.
A caveat for all drivers: the highest mode doesn’t necessarily produce the best results. Often modes 3 or 4 produce better mileage, depending on the vehicle and environment. The best practice is to experiment and track your results for at least two weeks in each mode.