The cars in GT4 dont look like the last 2 pics you posted, let me guarantee you. Since you're new you probably dont know about polygons and polycounts, correct? I'll run over this quick.
Polygons are flat planes with 3 (or more) sides, but when your making stuff for games (like GT4) they are all triangulated so for now lets say polygons are triangles. I'm
guessing an average GT4 model will have a polygon count between 1500 and 3000 polys, any more and the PS2 would lag to hell. Those cars you posted last use a modifier found in all the "main" modelling programs (such as Max, Lightwave and Maya - not z-modeler) which smoothes the mesh. This modifier curves corners and smoothes bumps, and it also RAMS up the polycount. You're usually looking at over one million polygons for a single car. These are just exhibition pieces, for portfolios of 3d models, animations or simply a hobby (most people do this for fun). If you tried to put on of these kinds of cars into GT4, your PS2 would probably explode or something. The cars in GT4 look good because of the Gran Turismo game engine, but they have only a fraction of the polycount the "meshsmoothed" models have. They wouldn't stand up against these high poly models in a render though, you'd be able to see lots of flat edges etc.
Simply put: Games use lowpoly models optimised to look great in the game engine, for renders you can do whatever the hell you like.
Now onto your questions. The main modelling programs are 3d Studio Max, Maya, Lightwave, Rhino and Softimage XSI (name any if i've forgotten some). Z-Modeller is great for games, but that's it. There are a few free programs you can use for game models (z-modeller included) such as Milkshape 3d or my favourite, CarEd.
3d studio max is more focussed towards polymodelling->meshsmoothing. It has nurbs functions but they suck balls. LW and Maya are much better at nurbs and rhino is dedicated to nurbs. Nurbs is something that is difficult to get to grips with but yields very awesome and perfectly smooth results, but i digress.
As for making cars look good, that's simply down to the user. Any program is only as good as the person sat using it. A veteran could grab Z-Modeller (see a bunch of people on this forum) and make a fantastic exhibition car that's too ridiculously over-detailed for games (but put it in one anyway
) and conversely, a noob could grab 3dmax and make a total ****box. It's all down to experience and talent.
Now onto pricetags. 3D Studio Max is around $3000 to buy, Maya is somewhere in the region of $1000-2500 but as far as the rest go, i'm not sure. I think Rhino is the cheapest but feel free to prove me wrong. Most people get them illegally (warez), but of course i'm not going to tell you how or where to get them.
Your best start would be something like Z-Modeller (a free download and that 1st pic is a screenshot from z-mod). It caters for most modelling needs and has loads of export types should you ever want to test your cars in games. Once you get the means (or if you're crazy/corporate funded) you should grab one or more of the "expensive" programs. They're harder to use but because of the huge amount of online tutorials you'll soon have the basics down.
What an essay, LOL. I wish i could babble crap like this for my college essays, i'd have a 2000 word one done in just an hour
. Anyway i hope i answered yer questions, i just hope you read all that crap :roll: