if you have an application named Car (i.e. created by rails new Car), nifty generators allow to create a Car model, which will not work since Car module is already defined
~/Sources/Car$ rails g nifty:scaffold Car url:string
the standard generators will not allow this:
~/Sources/Car$ rails g scaffold Car url:string
The name 'Car' is either already used in your application or reserved by Ruby on Rails. Please choose an alternative and run this generator again.