How to target many geo kw's under a category or subcategory?

Trying to build a general information portal website, have done kw research but can't decide on weather to have subcategories on the site or only categories. Bc 1 of the categories is very broad, let's say Cars, and then a subcategory of that would be a local service regarding cars. But this service can be in many different cities in that country so many geos. How to go about this? So the category will target 'Cars' as kw and the subcategory 'service x cars' but then what about each page in that subcategory? If each page targets only 1 'geo + service x cars' I'm afraid the page will end up w/ not much text which makes it harder to rank.
But on the other hand, if I have several geos on 1 page that makes it tougher to optimize the page for each geo like kw in Title, H1 etc.
So how to deal w/ targeting so many geo kw's in this same niche under that category or subcategory?
And how can you write enough text for something like this?

 

There is also a problem if Google would consider that kind of content a so called "doorway pages". Google it to understand better.

Maybe you could try something like this: Make one page/category for "service x cars" and than create another page with a huge list of geographical locations and if neccessary a links for specific car shops. You can than make an internal link from "service a cars" page to a page with cities/car shops list.

Traying to rank for each location can get your website into algorithm penalty and destroy all your business building effort.

 

I suggest creating such structure - cars/servicexcars/area/page. That's quite deep, but you can rank the 'area' page for different regions. It might look like a list of services in a particular area with some concise description and a link to a certain service.

 

Thanks for your reply but I don't understand what you mean. Do you mean that each main region consists of smaller areas? How can I rank the area page for diff regions?
And why a list of services? bc the service is already 'service x cars'.