The only thing you know for sure about Collection is that it is a collection of Vehicles, or a collection of a supertype of Vehicles. So the only thing you know for sure that you can put into this collection are Vehicles. So you are allowed to pass a Collection of NonLifes to the method, but you may still only put Vehicles or subtypes into the collection within the method.
In general: with super, you can put values of the mentioned type in it, or subtypes. With extends you can retrieve the mentioned type from the collection, or retrieve them as a supertype.
