Tabela1:
 Id int A_I;
 Modelo varchar;

Tabela2:
 Id int A_I;
 Id_fk int (foreign key da tabela1);
 cor;

SELECT * FROM Tabela1 JOIN Tabela2 ON Tabela1.id = Tabela2.Id_fk;

$selTab1 = mysqli_query($conn, "SELECT * FROM tabela1;");
$dataJoin = array();
while ($rowTab1 = $selTab1->fetch_assoc()) {
    $selTab2 = mysqli_query($conn, "SELECT * FROM tabela2 where Id_fk={$rowTab1['id']};");
    if($selTab2->num_rows > 0) {
        $rowTab2 = $selTab2->fetch_assoc();
        $dataJoin[] = array(
            'tab1_id' => $rowTab1['id'],
            'Modelo' => $rowTab1['Modelo'],
            'tab2_id' => $rowTab2['id'],
            'cor' => $rowTab2['cor']
        );
    }
}
echo '<pre>', print_r($dataJoin), '</pre>'; // aqui já vai ter os dados das duas

$selTab1 = mysqli_query($conn, "SELECT * FROM tabela1;");
$dataJoin = array();
while ($rowTab1 = $selTab1->fetch_assoc()) {
    $selTab2 = mysqli_query($conn, "SELECT * FROM tabela2 where Id_fk={$rowTab1['id']};");
    while($rowTab2 = $selTab2->fetch_assoc()) {
        $dataJoin[] = array(
            'tab1_id' => $rowTab1['id'],
            'Modelo' => $rowTab1['Modelo'],
            'tab2_id' => $rowTab2['id'],
            'cor' => $rowTab2['cor']
        );
    }
}
echo '<pre>', print_r($dataJoin), '</pre>'; // aqui já vai ter os dados das duas