The Ultimate Driving Machine sucks in terms of reliability. I bought my first and last BMW 3.5 years ago while it was still under their their Warranty/Maintenance plan. However, I have had leak after leak before and after the warranty expired. I think I have replaced the whole cooling system and oil system. Every day before I drive my car, I have to check the undercarriage plate to see if I got another coolant or oil leak. Plus the "engine malfunction, increased emissions" light always come on and the engine start shaking and its always caused by a different part. Do not buy unless you plan to buy several extended warranties and pray the parts are covered.
I love the sporty design and the interior.
Build a better engine but I does not matter cause this my first and last BMW.