An auto DC adapter has a cigarette lighter input plug on one end that is plugged into the cigarette lighter receptacle and on the other a special output connector that is plugged into the laptop's power receptacle. Although recent P4 laptops have higher and higher power requirements, auto batteries have the capacity to supply the necessary output for the PC.

BENQ
    Benq JoyBook L41,
    Benq JoyBook Q41,
    Benq Joybook DHP400,
    Benq Joybook DHR400,
    Benq Joybook DHS400,
    Benq Joybook DHU100,
    Benq Joybook X31

    Benq Joybook A Series
        Joybook A32, Joybook A33, Joybook A33E,
        Joybook A52, Joybook A52-T25

    Benq JoyBook C Series
        JoyBook C41, JoyBook C41E, Joybook C42,
        Joybook C42-101

    Benq Joybook Lite U Series
        Joybook Lite U101, Joybook Lite U101-SK02

    Benq Joybook S Series
       Joybook S31, Joybook S31-C02, Joybook S31V,
        Joybook S32, Joybook S32B, Joybook S32EB,
        Joybook S33, Joybook S35, Joybook S41,
        Joybook S41-140, Joybook S41-146, Joybook S41-310,
        Joybook S41-322, Joybook S41-324, Joybook S41-335,
        Joybook S41-357, Joybook S41-412, Joybook S41-424,
        Joybook S41-425, Joybook S41-448, Joybook S41-C05,
        Joybook S41-T34, Joybook S41-T44, Joybook S42,
        Joybook S73G, Joybook S73G-C27

    Benq Joybook T Series
        Joybook T131P, Joybook T132, Joybook T31