Hello Viktor & Rudi

I want to create 4 different websites

cars.domain.com
jobs.domain.com
ads.domain.com
rs.domain.com

with 4 different admin panel settings Logo, Colors, Custom fields, Maybe different Templates and etc... just for users i want to by one username & password they can access to all 4 websites.
as i see this is not easy and need customization and customization is not free... and i change my mind
also tested to install 4 script in subdomain directories but how to SYNC usernames & Passwords in DB ?