I'll start off by stating the nature of the problem.
My client has a pre-existing website that allows a user to select a vehicle from a number of drop down lists that tunnel down until they display a list of different types of a certain vehicle model.
Alfa Romeo (brand) | -> 145 (model) | -> 145 1.9 JTD 8V -> 145 1.9 JTD 12V (not real but an example)
Once the user has select a vehicle and the "sub variant" (for lack of a better word) of that vehicle they are directed to a page that displays a list of products that a compatible with it.
On top of this, the products that a shown that a compatible with it directly affect the vehicles performance and the gains in power and possible gains in MPG performance are displayed alongside a product.
Their existing website uses a very old system that isn't worth salvaging
So in Magento I am not tasked with creating a near enough identical vehicle selector system that displays compatible products with that vehicle and how it affects the performance of that vehicle.
I have tried to use just categories but could see no way of showing the unique product to vehicle performance improvements, there are different products that affect a vehicle, simple idea is that the more expensive products do better than the others (no surprise there).
I have also looked in to create a custom module that adds a few database tables that hold information about Manufacturer, Model and Subvariant to be queried by a front-end block/widget but with one hurdle; that a new custom attribute would need to be created that could be easily edited similarly but not necessarily identically to how categories are managed (with the tree view that is very user friendly compared to a very long multi select).
Any advice or pointers would be greatly appreciated, I've started out with Magento with what I would have to say is a very hard project for a first timer with the system, I have spent a few weeks reading up and learning modules development.