I would have to agree with most of you; it comes from a love of cars in general. My dad owns an auto repair shop, did so before I was born, and before that was a total gearhead since his own childhood (when he, too built models). It was actually some family friends who got me my first model as a birthday gift. I thought it was kind of fun (but still preferred my Legos, from which I engineering anything imaginable, but mostly realistic stuff). As I built more models, I soon alternated between models and Legos during the summer. Now, the Legos are boxed up in a closet somewhere, and my model desk looks like a mini-nuke was dropped on it
Since I love cars and machinery in general, but am not a millionaire, I build models of cars I will never own and many never see in real life (which seems to be a common reason here). The fact that I can (well, not yet, but once I get around to it
) look at a Mercedes CLK-GTR Le Mans race car (a very sleek, wicked looking car) from all angles, under the engine lid, and even the undertray, is reason enough to build. I'll never see that car in real life, or if I do, it will be squeezed in a crowd of people behind a cordoned-off platform. As a modeler, I can not only look at it from every angle and stance, but know that I was the one who built it. That's my primary reason.
The other reason is that it's just a part of my personality. I'm headed off to college in mere days to start the 4-year process of getting my mechanical engineering degree. I just like to design and build things.
Alex