He prays Zuhr in his car because he is the only Muslim in the factory
Question

                Iam at work during time of zuhar salah. during my lunch break i go and offer salah in my car in the back seat in sitting positon. All factory workers are kafirs and i am the only muslim here. is it permisible.
Praise be to Allah.
      Firstly: 

    Standing when offering an obligatory prayer is an essential 
    part of the prayer and it is not permissible for anyone to pray sitting 
    unless he is unable to stand, or standing will be very difficult for him, or 
    he has a sickness which it is feared will be made worse if he prays 
    standing. 

    The basic principle concerning that is the report narrated by 
    al-Bukhaari (1050) from ‘Imraan ibn Husayn (may Allah be pleased with him) 
    who said: I had haemorrhoids so I asked the Prophet (blessings and peace of 
    Allah be upon him) about prayer and he said: “Pray standing, and if you 
    cannot then (pray) sitting, and if you cannot then (pray) lying on your 
    side.” 

    Ibn Qudaamah (may Allah have mercy on him) said: The scholars 
    are unanimously agreed that if a person cannot stand, he may pray sitting. 
    The Prophet (blessings and peace of Allah be upon him) said to ‘Imraan ibn 
    Husayn: “Pray standing, and if you cannot then (pray) sitting, and if you 
    cannot then (pray) lying on your side.” Narrated by al-Bukhaari and Abu 
    Dawood, and by al-Nasaa’i who added: “If you cannot, then lying on your 
    back; Allah burdens not a person beyond his scope (cf. al-Baqarah 2:285).” 
    And Anas said: The Messenger of Allah (blessings and peace of Allah be upon 
    him) fell from a horse and injured his right side. We entered upon him to 
    visit him, and the time for prayer came. He prayed sitting, and we prayed 
    behind him sitting. Agreed upon. 

    If he can stand but is afraid that doing so would make his 
    sickness worse or would delay his recovery or would be too difficult for 
    him, then he may pray sitting. Something like this was stated by Maalik and 
    Ishaaq. End quote from al-Mughni (1/443). 

    Al-Nawawi (may Allah have mercy on him) said: The ummah is 
    unanimously agreed that if a person is unable to stand during the obligatory 
    prayer, he may pray sitting and he does not have to repeat it. Our 
    companions said: His reward will be no less than his reward if he prayed 
    standing, because he is excused. End quote from al-Majmoo‘ (4/201) 

    Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: The 
    same applies to the one who is in a state of fear and cannot pray standing, 
    such as if he is praying behind a wall and around him is an enemy watching 
    out for him, and if he stood up he would appear from behind the wall but if 
    he sits he will remain hidden from his enemy by the wall. In this case we 
    say to him: Pray sitting. 

    This is indicated by the verse in which Allah says 
    (interpretation of the meaning): “And if you fear (an enemy), perform 
    Salaah (pray) on foot or riding” [al-Baqarah 2:239]. So Allah waived the 
    obligation to bow, prostrate and sit, and also to stand if he is in a state 
    of fear. End quote from al-Sharh al-Mumti‘, 4/461. 

    The fact that you are the only Muslim worker in this factory 
    does not make it permissible for you to pray sitting in your car; rather you 
    should pray in any clean place inside or outside the factory, offering the 
    prayer in full and without rushing. 

    It does not seem from your question that you are afraid of 
    showing your Islam or praying openly; that is something very unlikely in 
    your country. If we assume that a Muslim is living in a land where he cannot 
    pray openly, then he must migrate from that land to a country where he may 
    practice his religion openly. 

    So fear Allah, may He be exalted, and try to perform your 
    prayer as Allah has enjoined, and beware of neglecting it or being heedless 
    with regard to its times and essential parts. 

    We ask Allah to guide us and you and to make us steadfast. 

    And Allah knows best.