Originally Answered: I need help picking out a new car?
Both the G35 and the GTI will be considered sports cars and will bite you hard on insurance.
The Infiniti is likely to have higher miles and be in need of more "small things" over the next five years, like shocks, brakes, gaskets... all of which will require pulling things apart, meaning labor charges. An independent mechanic will charge less, but the work will still have to be done.
You're a student and you make $1000 per month. Common wisdom is that you shouldn't pay more than 15% of your gross monthly income on a car payment. (It's actually supposed to be car expenses, including gas, insurance and maintenance, but that is unrealistic.) That's a car payment of $150 per month, which works out to $7000 over four years if you put $500 down. It's a bad idea for students to take on a car loan, unless it's a short-term one (2-3 years) to build your credit. Many of them have student loans, and experience tells me that Stafford loan interest will NOT stay at 2.5% forever.
I worked at a Walmart for a time during college. Our parking lot had GTIs and G35s, but the single college students didn't drive them. We drove Sentras, Corollas, Hyundai Tiburons, Civics, Cavalier Coupes, Subaru Imprezas and the like.
If you want a sporty little car, look for a Nissan 200 SX SE-R, or a 240SX. If you want an Infiniti, look for a G20t (rare, but pretty quick). Look for a Honda Accord with the V6. See if someone is selling a Fox-body or '94-04 Mustang with a V8 for cheap.
In other words, buy a cheap car right now. Use it to build up a good driving record and good credit, and when you graduate and get a good job, you'll be able to more easily afford a nice car. Maybe a really nice car.
One more thing: Read "Made in America," the book Mr. Sam wrote, cover to cover. They usually have it in paperback on the book aisle. Walmart doesn't talk about him much anymore, but there's a lot of good life lessons - and good stories - in that book.