To begin with, it is important to keep in mind that your device only reports its location every two minutes; when you look at the history, you must therefore keep in mind that the movements that take place between the updates are not logged. Therefore, it can sometimes look like the vehicle has "taken the path as the crow flies". It should also be noted that all GPS receivers have a certain margin of error, sometimes up to 15 meters, depending on the coverage where the product is used.
If you experience a consistently poor precision of the location, it may have to do with the signal strength. Initially try to adjust the placement, you can also read the following article for general suggestions on how to improve the accuracy.