wp_query.php

<?php

function get_cars() {
    $ne = $_REQUEST['northeast'];
    $sw = $_REQUEST['southwest'];

    $args = array(
        'post_type'         => 'car',
        'post_status'       => 'publish',
        'meta_query' => array(
            'relation' => 'AND',
            array(
                'key' => 'locationlat',
                'value' => array($sw[0], $ne[0]),
                'compare' => 'BETWEEN'
            ),
            array(
                'key' => 'locationlng',
                'value' => array($sw[1], $ne[1]),
                'compare' => 'BETWEEN'
            ),
        )
    );

    $query = new WP_Query($args);

    $cars_inside_bounds = [];
    $carIds = [];

    while ($query->have_posts()) {
        $query->the_post();

        $car_info = array(get_field(CAR::LOCATIONLAT), get_field(CAR::LOCATIONLNG)); //makes location string into lat and lng array

        $carImages = get_field(CAR::GALLERY);

        array_push($car_info, get_the_ID());
        array_push($car_info, get_permalink());
        array_push($car_info, get_field(CAR::MODEL));
        array_push($car_info, get_field(CAR::RENT_PERDAY));
        array_push($car_info, $carImages[0]['sizes']['large']);

        array_push($cars_inside_bounds, $car_info);
    }

    print_r(json_encode($cars_inside_bounds));

    die();
}

function get_cars_if() {
    $ne = $_REQUEST['northeast'];
    $sw = $_REQUEST['southwest'];

    $args = array(
        'post_type'         => 'car',
        'post_status'       => 'publish',
    );

    $query = new WP_Query($args);

    $cars_inside_bounds = [];
    $carIds = [];

    while ($query->have_posts()) {
        $query->the_post();

        $car_info = array(get_field(CAR::LOCATIONLAT), get_field(CAR::LOCATIONLNG)); //makes location string into lat and lng array

        $lat = $car_info[0];
        $lng = $car_info[1];

        if ($lat >= $sw[0] && $lat <= $ne[0] && $lng >= $sw[1] && $lng <= $ne[1]) {
            $carImages = get_field(CAR::GALLERY);

            array_push($car_info, get_the_ID());
            array_push($car_info, get_permalink());
            array_push($car_info, get_field(CAR::MODEL));
            array_push($car_info, get_field(CAR::RENT_PERDAY));
            array_push($car_info, $carImages[0]['sizes']['large']);

            array_push($cars_inside_bounds, $car_info);
        }
    }

    print_r(json_encode($cars_inside_bounds));

    die();
}

add_action('wp_ajax_nopriv_get_cars', 'get_cars');
add_action('wp_ajax_get_cars', 'get_cars');
add_action('wp_ajax_nopriv_get_cars_if', 'get_cars_if');
add_action('wp_ajax_get_cars_if', 'get_cars_if');