A sliding window assembly for a vehicle includes a frameless fixed portion having first and second glass window portions and includes a sliding portion having a glass window panel. The sliding window assembly is a horizontal sliding window assembly and is configured for mounting at an opening of a bodywork of the vehicle. Upper and lower track members are adhesively attached at the rear surface of the first and second fixed glass window portions and no portion of the upper and lower track members is in contact with the front surface of the first and second fixed glass window portions. A glide member is longitudinally movable along the lower track member to facilitate movement of the glass window panel between its opened and closed positions. The fixed portion is adhesively bonded to the bodywork at a frameless periphery of the fixed portion that faces the interior of the vehicle.