I would like to know if some word is present in the URL.
For example, if word car is in the URL, like www.domain.com/car/ or www.domain.com/car/audi/ it would echo 'car is exist' and if there's nothing it would echo 'no cars'.
Try something like this. The first row builds your URL and the rest check if it contains the word "car".
$url = 'http://' . $_SERVER['SERVER_NAME'] . $_SERVER['REQUEST_URI'];
if (strpos($url,'car') !== false) {
echo 'Car exists.';
} else {
echo 'No cars.';
}