You have some real world track experience. And that's something that 9 out of 10 guys who talk big will never have. But don't lose sight over what makes a track car, a track car. Forget about how it looks. And while it could be argued many different ways, what really matters...
is this...
...and this...
...and this...
THAT is what makes a track car.
And all of those are pretty much incompatible and in fact, out right, life threateningly dangerously when installed in a road car. A road car being used and driven on public roads. Unless of course you're WEARING a helmet on the road. Which is illegal.
Road cars make lousy track cars. And vice versa. If you really want to turn the A6 into a track car, it can be done. But the first step should be to take it OFF the road and strip it out. Like most cars, even cars with 'sporty' intentions, it's WAY too heavy (both overall and nose heavy). By removing the door innards, seats, a/c, radio, airbags, sound deadening, etc, you should be able to shed a few hundred pounds, even with the addition of a full cage. When you're down to < 3,500-lbs including you as the driver, I think the car will be a lot more interesting. And certainly better balanced.
But do me one favor, get rid of those ridiculous canards. They're pointless. And they're not doing anything. When you have a large front splitter and a large rear wing (on a car with a properly tuned suspension and sticky tires mind you), the purpose of those canards is to help fine tune and balance the downforce between front and rear. Think of it like trim. On their own, they're really not doing much of anything but adding drag. And they just look silly.
I think an A6 track car is a novel concept. And something worth pursuing if you either have the money or your parents are completely and totally insane enough (OK fine)
willing and supportive enough to indulge your endeavor. A guy from NASA NE did the same thing a few years back with a Chrysler 300.
Just don't underestimate the cost and commitment involved. There's a reason people tend to buy used track cars that somebody else already developed. Because while putting one together has obvious advantages, it's a money sucking black hole that you'll likely never fully recover from.
) Been learning how to drive for the past few months, and I think I've started to fall in love with this thing! Already changed a few things out on it. I still want to add a 
sticker to the rear window. 
