wpcm-custom-filters.php

/**
 * Adding custom filter to WP Car Manager
 */
add_action( 'wpcm_listings_vehicle_filters', 'wpcm_custom_template_vehicle_listings_filters_color', 14 );

function wpcm_custom_template_vehicle_listings_filters_color() {
	wp_car_manager()->service( 'template_manager' )->get_template_part( 'listings/filters/color' );
}

add_filter( 'wpcm_get_vehicles_filter_color', 'wpcm_custom_filter_color', 10, 3 );

function wpcm_custom_filter_color( $filter, $key, $val ) {

	$filter['key']   = 'wpcm_color';
	$filter['value'] = sanitize_title( $val );
	$filter['type']  = 'CHAR';

	return $filter;
}