Using AND and bracket grouping in SQL not working

You need 2 table joins since there are effectively 2 meta keys in your WHERE clause:

SELECT DISTINCT
    SQL_CALC_FOUND_ROWS wp_users.*
FROM
    wp_users
        INNER JOIN wp_usermeta AS um1 ON (wp_users.ID = um1.user_id)
        INNER JOIN wp_usermeta AS um2 ON (wp_users.ID = um2.user_id)
WHERE
    (wp_users.user_login LIKE '%little%'
        OR wp_users.user_email LIKE '%little%'
        OR wp_users.user_url LIKE '%little%'
        OR wp_users.display_name LIKE '%little%'
        OR (um1.meta_key = 'first_name'
            AND um1.meta_value LIKE '%little%')
        OR (um1.meta_key = 'last_name'
            AND um1.meta_value LIKE '%little%'))

  AND((um2.meta_key = 'car_type'
    AND um2.meta_value LIKE '%Camry%')
    OR(um2.meta_key = 'car_type'
        AND um2.meta_value LIKE '%Toyota%'))
ORDER BY
    user_registered DESC