The video shows how ordinary elastic straps, often used to secure shopping on the back of bikes, can easily be torn by the force of a fast-moving Christmas tree.
It is important for people to stop for a couple of minutes and take the time to tie their tree to their car properly, Christian Buric of the ADAC motoring group told The Local.
"We don't have any record of fatalities from this kind of accident, but you can see in the video that even at relatively slow speeds of 30 or 40 kilometres an hour, when a car stops suddenly, a poorly-secured tree can shoot off the front like a rocket."
He said the ADAC had carried out the crash test to show people just what a risk poorly secured trees could pose to pedestrians or cyclists in the case of an emergency stop.
"Even in the middle of a stressful day buying a tree, we are calling for people to just take the time to make sure they have a proper belt - and that then also take the time to ensure they fix the tree to their car properly," said Buric.
This means having the cut-off end of the tree trunk facing forward and not only strapping belts over the main tree body, but also wrapping one around the tree's trunk so it cannot slip through if the car stops suddenly.
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If a tree is small enough to fit inside the car, that is also a better idea he said. But a board should be placed between the tree trunk and the front seat so that the tree cannot spear anyone in an accident.