We ask Allah to guide you, and we appreciate your eagerness to find out what is right.
With regard to using work equipment for personal ends, that is not permissible except with permission from the boss or someone who has authority to give such permission.
If the one who has authority over these things gives permission to use them, and he has the authority to give them to employees outside of working hours, then there is nothing wrong with your using them, because they are the property of the company and it may dispose of them by renting them out, giving them away, and so on.
See the answer to question number 121959.
Based on that:
With regard to the privileges that have been given to you by the foreign company - such as a mobile phone and car - there is nothing wrong with you using them, according to the agreement that the company has with you. If the company allows you to use them for work purposes only, then it is obligatory to limit it to that. If these privileges are a gift from the company and they have allowed you to use them in all cases, it is permissible for you to use them.
There are some differences between the public and private sectors with regard to using things for personal ends that were given by an institution or company.
In the case of private companies, if the boss gives permission to use them for personal ends, there is nothing wrong with that, as stated above.
But in the case of the public sector - or government - even if the boss gives permission for that, it is not permissible to use them in such ways that they are consumed or used up. The reason for that is that this is public wealth and it is not owned by any particular person who could give permission to anyone to use it for personal ends.
And Allah knows best.