Should I buy a PS4 or Upgrade my Car Stereo?

I'm a guy and just turned 19.
Just got a best buy gift card tonight and was thinking what to get.

With the budget I have, I have an option of getting a PS4 or getting an upgrade to my Civic coupe's sound system.
Since I already have a PS3, I was thinking would PS4 really be a bigger upgrade because I don't really want to get a PS4 at this moment if it's not a big upgrade and i'm surely comfortable to sticking to my PC and PS3 gaming for a while.
If I go with the PS4, then I'll have to get 2-3 new games.

I bought a preowned '08 civic coupe LX a few months ago, and the Aux and CD function has not been working since then. I've been bored by listening to radio all the time and was thinking this might be a good upgrade since I'll be getting a new car stereo receiver, new car speakers, amplifiers, and subwoofer setup which all together is $410 something.
But I'll get bestbuy to install it which will cost $230 for the whole setup or I could look for cheaper alternatives.
Or I could just get my current car stereo receiver fixed for <$100 and get the PS4 or something else.

What other options do you suggest?
I'm a 19yr old guy, have a $500-600 budget.
I already have a gaming PC, PS3, iPhone etc so don't suggest any of that. But I prefer electronic stuff.
Hope to get some good ideas, thanks!

Honestly I don't think that the PS4 is that big of an upgrade… But i would go w/ the new stereo system… I just upgraded my stereo system…