Several of my friends track 370zs. When you start to get fast as my friends do, you start to discover limitations in ALL street cars. No question the Zs overheat and need a supplemental oil cooler. They also need a bigger radiator. My friend has a problem with his CV joint now. A friend just blew a motor in his 370 so they also suffer from oil starvation problems. They are considerably lighter than the M3 and have much superior brakes.
A well driven Z can be very, very fast at a track and can easily keep up with or run faster than an M3. M3s are not without their share of problems as well. The brakes are entirely inadequate for track purposes and almost everyone runs a BBK setup to avoid destroying the rotors. The stock suspension is also poorly suited for track duties. The extra weight becomes very noticeable at speed. Consumables in the M3 are also considerably higher because of the extra weight. This becomes more of an issue the faster you get.
Corvettes while also very fast, tend to burn through a lot of expensive consumables as well. It's also a rare day when I DON'T see a Vette with a blown motor at the track. They suffer from severe oil starvation problems when you start go get fast.
Are you out to have fun? My advice - get a Miata and learn how to drive first. Rotors are $15 and it won't burn through a lot of gas or brakes because it's so light. You can have a LOT of fun in a Miata and learn to get very fast while spending 25% of what you would in an M3.