The answer to that question, is no, absolutely not. Don’t do it!
You can buy a new car that will be available for years, whereas the vehicles in your stable would be much tougher to replace. This hobby (addiction?) is not a wise financial decision, but I do have to point out: the 3 cars you currently own have not only fully depreciated, they’re likely appreciating in value… whereas a brand new $70,000 BMW will plummet like a rock as soon as it gets out of the warrant period.
As far as track cars go, well, you already own The Answer…
Not counting my wife’s cars, I’m currently in a 4 car situation, where each car has it’s own purpose:
-AP2 S2000 for my fun, top-down, mountain road car and date nights with the wife car. There’s a good chance it’s my forever car, as I’ve owned it longer than anything else in my stable. I’ve driven everything under the sun, and nothing puts a smile on my face like my AP2 when driven in anger on a twisty road.
-E82 BMW 128i has become my semi-daily (I technically have a work car that I commute in). It’s just good everywhere. Comfortable, easy to drive, fun, good visibility, could take a road trip anywhere without complaint, etc. I still have plans to tinker with it, but nothing too extreme.
-DC2 Integra GS-R is rapidly becoming a track car to run NASA TT6 and autoX locally. Because I have other options, I don’t mind that it’s becoming more compromised.
-Nissan Xterra. I bought this thing dirt cheap as a winter beater. It can tow 5000 lbs in a pinch. I don’t care if it gets beat up in the winter and I can get most Home Depot runs done in this thing.
If you’re not tracking a car, and don’t live in a place where it snows, I can see some consolidation… but otherwise, I wouldn’t want to do it.