Please note that for this article, we will be referring to the Spytec GPS GL300 Tracker.
When placing the GL300 on a vehicle it can be confusing as to where to put the tracker and why. To do its job properly, the tracker needs to be able to connect to the satellite network and transmit data back to our servers, so we need to make sure the tracker is positioned in a way that gives it the best chance to do that.
The most common, effective placement of the GL300, is pairing the tracker with an M2 case (M2 Case on Spytec.com). The M2 case allows you to place the tracker on the outside of the car, typically underneath on the undercarriage. 
When placing the tracker underneath the car, it is important to make sure the case is attached to the frame rather than the suspension. The suspension will move independent of the frame, making the attachment less secure. Note: Please refer to your vehicle's information for specifics. The most common placement is towards the rear of the car on the frame that runs along the outer edge of the chassis, but this will depend on your specific needs.
Another possible placement location is inside the vehicle itself. This can allow you to be more creative with the placement of the tracker and have a touch more flexibility in where the tracker is. Ideal placements for the interior of the vehicle can be under the passenger or driver seat or hidden inside the dashboard. The tracker can also be hardwired to the vehicle’s electrical system for extended battery life. (Hardwire Kit on Spytec.com)
There are also spots where the tracker should not be placed. For instance, the GL300 should not be placed in the trunk of a vehicle because the trunk tends to negatively affect the ability of the tracker to connect to the needed networks and can lead to poor performance. Locations that are fully enclosed in metal can be problematic as well, such as the stereo bay in the dash. Another thing to factor in is heat. Battery-powered devices do not like hot environments, which is why we typically do not recommend installing the GL300 in a vehicle engine bay. If an engine bay deployment is needed, the Hardwired GPS Tracker is much more suited to that environment.