My M3 was one of the first 300 ever built, I bought it with 19k miles on the clock from a BMW dealer as a CPO car and it has had a BMW warranty ever since it was new. I maintain all my cars at my local BMW dealer and keep up on all servicing on time and never scrimp if work needs doing (not that it has outside consumables). That's smart motoring in a class car. You obviously don't actually even enjoy cars if everytime you get in the door you crap your pants about how much it's worth. I'd rather drive a Nissan if I gave a hot shit about that, but I have more self respect and enjoy cars/driving.
You bought a cloth seated Nissan brand new, sucked down the huge depreciation and think that's smart? When you jack it in at three years it will have cost you $6k a year minimum to run it. My car costs me nothing per month bar insurance and usual costs, and I get a car allowance from my employer, which I can pocket AND a fuel card for free fuel. Yeah, that's the deal, I get a very fast, luxury ride and you get a Datsun with shopping cart steel wheels and manual windows.
Tell you what, you should probably not be working in the financial arena as you appear to have the financial acumen of a wounded Badger.