How to query comments only for the current post?

I am using ACF and my comments have custom fields. I also have custom post type called cars.

What I'm trying to do is to make users comment their average consumption, and then I calculate average consumption for single car.

I did that, and it works well except one part. Average consumption is same for all cars, even each car has different average consumption.

For example:

• Car 1 mpg (28;25;39 - avg 30.6)
• Car 2 mpg (44;50 avg 47)

And when user goes to Car 1, avg should be 30.6 and Car 2 should show 47. Instead each car has same value and it's avg mpg on from all fields (28;25;39;44;50 avg 37.2)

Here is my code. I have followed ACF documentation on getting values from comments

 ?php
$args             = array();
$comments_query   = new WP_Comment_Query;
$comments_count   = wp_count_comments();
$comments         = $comments_query-query($args);
if ($comments) {
    foreach ($comments as $comment) {
        $total += get_field('mpg', $comment);
    }
} else {
    echo 'No comments found.';
}
$average = $total / $comments_count-total_comments;
echo round($average, 2);
wp_reset_query();
?

This code is in single-cars.php (custom post type) and it does the calculation but from all comments for all posts, and I want to show calculation for single car.

Thanks in advance