Cheap, reliable as a fork, parts everywhere, unassuming, can work on it blind folded, and more or less expendable.
For me it goes a little further that it was my first car that I've just kept all these years and it has never let me down and I have a small guilt complex with the idea of abandoning it or throwing it away.
Anything nicer like a M3 that would be a nice middle ground between the two and I'm in the same boat, it wouldn't be driven in monsoon weather or working where it would see short stop/start type driving all day, etc. Doesn't matter what else I have, a true beater is still required.
Unlimited or not, if you're putting a built motor and turbos into a newly purchased ~$20k car like a 350Z, you're already pretty commited. Might as well go to the finish line and not settle for holding your ground with stock cars that are most likely to be gunning for you, that's all I'm saying. Zivic needs to fix his traction issue once and for all and be happy that hardly anything new can touch him, not second guess himself for going too far and thinking that "just enough" would have been better.