I wouldn't recommend a Z as your first car either. It has just way too much horsepower and torque to be messed around with like most first cars are driven. I had an 02 Altima as my first car. Guess what, drove it into the ground. Blew a head gasket and ended up selling the thing for a down payment on a barebones ford ranger (job wasn't what it is today). As time went on and I had that truck for about a year and a half, I had a new job at this point making twice as much as I did at my previous job, which put me in a better situation to make a move towards a new car. Of course this is also excess over all the necessary bills; rent, utilities, insurance, gas, food, misc. items.
I know only being 20, I am in that category of being a teenager and having this car, but the fact of the matter is, I'm self-supporting and pay for the car myself. When you actually pay for a car yourself and invest big amounts of money into it, it makes you drive it completely different than if it were a gift from your parents; and its because if you end up doing something to screw it up, you not only have to pay to fix it but also have to still keep paying your monthly payment.
I do think this car should be one you earn just because at that point you've done your research and gone through the driving experience to realize the amount of respect you have to have driving a machine like this on the road.
I'd suggest going with the 2016 Honda Civic Si that will be coming out soon if not already out. Its got about 210 hp and is plenty fast and plenty luxurious for a first car.
The Z is definitely a force to be reckon.
Woman charged in fatal 370z crash caught on dash cam