Weapon and player models require a conversion to MD3 in order for Quake 3 to display the animations correctly. Most mapmodels are better off as ASE but when part of the model (same with patchmeshes and non-quad brush faces) has a surface shader using autosprite, this will cause unpredictable results and an error in the game's console.

ASE misc_models can target certain func_ entities to operate with the entity. It only works for non-triggerable func_ entities like func_rotating and func_bobbing. func_ entities that are triggerable like func_doors won't work with this method because the entity is expecting a targeting trigger instead of the model. Instead, you have to attach a model with the func_ entity's model2 key. Problem is, the model2 key only supports MD3 files, so you have to convert your ASE model to MD3 to get this to work.

if the car is both outside the playable area and only in a low light enviroment, do you really need the nuance of the 2006 model over the 2010? just get the base model done, noone will ever see the finer details anyway.

especially since you already decided to go lowpoly.

I modeled some vehicles last summer in my internship, and I confirm, doing it right requires some time.

modeled from orthographic reference of course, with some photos to get the details on the textures right

Always having to use orthographical references when modelling... For making texture an UV editing and making proper texture with Photoshop would be better than photos. You can take photos for color resources, however...