Please pay attention to the following points when placing anything in the car:
1. Sight range: ensure that the crutches will not block the driver's sight, so as not to cause driving danger.
2. Safe storage: ensure that the crutches will not slide or move when the vehicle is running, so as not to cause danger to the driver or passengers.
3. No obstacle: ensure that crutches will not prevent passengers from getting on and off or entering and leaving other places.
If you find it difficult to meet these requirements, or worry that this crutch will bring you security risks, then it is best not to use it in the car. Consider putting it in other places, such as the trunk outside the car, or keeping it as a souvenir at home.
In a word, the most important thing is to ensure the safety of yourself and others, and to respect your grandfather as well as your own and others' lives.