I am very surprised not to get DS models upon generating ember-cli model
ember -v
ember-cli: 2.4.3
node: 5.10.1
os: darwin x64
ember g model rental
There is nothing wrong with the generated code :)
Ember Data has been made an addon, and part of that work was to tweak the public ES6 modules so everything doesn't hang off of the DS
object. Now you can directly import the Model
like in the first code sample you show.
I have opened an issue on the Guides repository to fix the Tutorial section of the guides.