Two ideas out there. One, if you are someone that can afford $75,000 cars every 3 or 5 years then drive your M3 as a DD and enjoy it, let it get weathered, worn, dinged, scratched, etc. Then trade and gets something else in 3, 5, 7 years and when it's warrenty is over or 50,000 miles or what ever.
If you're like me and this was a buy of a century (tax free+military discount of $8,000) and had the cash to put down on it and probebly won't be able to buy something of this caliber again if ever. Then do like I do, buy a beater for $5,000 or so. It'll run, drive it on bad weather days, daily to work, don't care what happens to it so you're not stressing everyday you're parked at work or daily rock chips, etc. And drive the M3 on the weekends, hot date, long road trips. Don't have to worry about it everyday, garaged, kept clean and washed only once a week instead of every 3 days due to the weather.
I plan on keeping it for many years, probebly for as long as it'll last. Next car is a Ferrari, right? Yeah, well what ever my next car is, I'll still have this M3 looking almost new in 10 years...I hope.
So it's all up to you, but trust me, I don't give a shit if I drive a beater, when I have an M3 in my garage. Plus it's kinda a nice treat to drive it on the weekends. Something else to look foreward to.
Just my 2Cents.