Hello,
You can choose how the device is deployed. It means that that there is no effect to measurements if top/bottom side points up or down.
For ECO driving to work properly, device connection pins socket must point towards the vehicles front side. Deviations of +/- 2o are allowed. But it should be as straight as possible.
Deviations of maximum +/- 15o are allowed.
Horizontal position must be as flat as possible – parallel with vehicle plain.