Okay, I've allready said a lot on this topic. Maybe way to much. But healthy conversation never killed anybody! The fact that we've wandered waaayyy off topic is besides the point!
Okay, I am starting to see the point Joe made initially through a part of Martian's last post (please excuse shortening of your name...). This might have just been my small-worlded thinking. I have not once built a road car, which may be why I missed the point. Yes, on road cars and "funny cars" you can go bananas. The sky is the limit, true. I think in that aspect Jeff pretty much nailed it. The genres are so different, you simply can't really compare them.
My history in modelling is relaively narrow. I have build A/C, then saw one race car. It was a 1:12 Tamiya JPS Lotus Mk iii. After building that, I was converted. I loved it so much, I recently bought the 1:20 version of the same kit, just to make up for how terrible an injustice I did to the 1:12! I will most likely end up doing the 1:20 one stacks better, despite less detail in the kit.
And yes, I do have a few a/c still in the to-do box. An extensive list of Jolly Rogers planes through the years are still waiting to be built, for the simple reason it happens to (don't laugh!) carry our family crest. I also recently bought my first armour kit. Just to see what it's like. And I have a few wooden boats (Artesania) in the cupboard as well. Have done one smallish one, two big ones waiting...
At this stage on my workbench, I am working on a WRC Subaru and a Ducati, both Tamiya with detail sets, as well as my first resin F1, a Studio 27 Renault R25. What draws me to it: simple - I have an interest in auto racing and I love the challenge of building a good model. Living in SA, I do not have the exposure to armour and A/C most of you have. Otherwise I might have done much more of that.
Another thing I agree with Jeff is the "closed" nature of an auto. With armour, a lot of detailing is done on the outside, maybe the "cockpit" inside, I know not. (Excuse my ignorance if I am incorrect.) With aircraft, there are cockpits and wheel wells that can get more detailed (and engines for prop a/c) that might get missed by the casual observer. With autos, as you could see on the links I provided earlier, most detailing are hidden. You work days and night to get a bike engine looking "just right"... then you slap a cowling over it! A superbly detailed cockpit in a DTM or WRC car gets lost, as does F! engin detail, etc.
We are all here because we love modelling. You don't come out to a place like the FSM forums (or any other) for another reason. I come here to learn and to share what I've picked up if I can help. I have huge admiration for all types of models. Be it a spacecraft, a battle-worn tank, or a new one, for that matter, ships of all sorts or an aircraft. I simply love a good model.
Different genres, different challenges...