您可以在一行中插入多个元素，只需以正确的格式插入即可：
插入x（列）值（x1）、（x2）、（x3）

$string = "";
foreach($cars_name as $car){
    $string .= "(" . $car . "), ";
}
$sql = "INSERT INTO car_data (cars_name) VALUES $string";

请注意，您不应该接受用户输入而不进行消毒。

要使用一个语句和mysqli准备的语句（代码中的注解）。。。

$cars_name = ["Honda", "Volvo"];
// Create an entry for each name
$params = str_repeat("(?),", count($cars_name));
// Build a bind for a list of strings
$binds = str_repeat("s", count($cars_name));
// Add the params to the insert (remove the last ,)
$sql = "INSERT INTO car_data (cars_name)
             VALUES ".rtrim($params, ",");

$insert = $conn->prepare ( $sql );
// Bind the parameters, using ... is the argument unpacking operator
$insert->bind_param($binds, ...$cars_name);
// Execute the SQL
$insert->execute();

更新：
如果数组中有两个数据项，则可以将上面的内容调整为。。。

// Source data - ensure that the two sets of data have the same number of entries
$car_data = [ 'cars_name' => ["Honda", "Volvo"],
        'cars_modal' => [ '2015', '2016' ]];
$car_count = count($car_data['cars_name']);
// Create an entry for each name (2 binds per entry)
$params = str_repeat("(?,?),", $car_count);
// Build a bind for a list of strings
$binds = str_repeat("ss", $car_count);
// Reformat data for binding (needs to be a single list of the data
// with cars_name followed by cars_modal for each entry)
$merged_data = [];
foreach ( $car_data['cars_name']  as $key => $name )    {
    $merged_data[] = $name;
    $merged_data[] = $car_data['cars_modal'][$key];
}   
// Add the params to the insert (remove the last ,)
$sql = "INSERT INTO car_data (cars_name,car_model)
                 VALUES ".rtrim($params, ",");

$insert = $conn->prepare ( $sql );
// Bind the parameters, using ... is the argument unpacking operator
$insert->bind_param($binds, ...$merged_data);
// Execute the SQL
$insert->execute();

当我想这样做时，我首先内爆这个数组，得到一个由（，）分隔的普通字符串，然后当我检索数据时，我再次内爆它们。

$cars_name = implode(',', $_POST['cars_name']);

结果将是

Honda,Volvo,Mercedes,Toyota,BMW

如果您想再次从数据库中获取数组，只需执行以下操作：

$cars_array = explode(',', $databaseObject['cars']);

结果将与您的第一个数组相同。