Saxon Genitive vs. Adjective Noun (Model Parameters vs. Model's Parameters)

The suggestions in this same forum say that the use of the phrase "the car's antenna" is correct.

Questions:

1. Nobody mentioned the use of "the car antenna" -- which to me would be much more natural, although not perfectly precise. It is clear that the particular "car's antenna" may be borrowed from e.g. a transistor radio, so that in that case "the car's antenna is a transistor-radio antenna". [Please correct all that is wrong here, and comment the use of the hyphen.]




2. I want to write a short and elegant title in a computer program that would describe "the parameters of a model". Is it correct to use:
   2.a The Model Parameters, or for short, and because it is in the title: Model Parameters;
   2.b The Model's Parameters, or for short, in the title: Model's Parameters.

By definition of the Saxon genitive, the more precise would be 2.b, correct? But when you Google "model parameters" and "model's parameters", you get about 3 millions for the (a) choice and 30 times less (a hundred thousand) for the (b). And I bet that most of the people wanted to say the same thing: "the parameters of the model", and were trying to abbreviate it. Was there anybody who wanted to say something like "the model-like parameters", or "modelish parameters" -- I guess no one!

The same thing applies to:

3.a The user password;
3.b The user's password.

Please comment heavily on the question 2. It would be nothing strange that most of the people just write what is common or simpler, but what woul the experts suggest? In cases like this, where the distinction is almost negligible, is it OK to go for the simpler solution. It also concerns another example from this pages: "The ProductName's Desgin" or "The ProductName Design".

Thanks in advance.