Ford (and GM's) main problem is that they're too big for the reality of the market today. EVERY industry goes through this... starts out with tons of small players, goes to a few mega players, eventually the field evens out. GM used to own more than 50% of the domestic market share - when you open markets, that position is not defensible. Market share WILL go down, and then you have to deal with the stuff in your closet (health care, union commitments, etc...). That's just how it is.
3 series might be a great success for BMW - their best selling car. BMW sold 142,000 units in '07 - it's best year, and it crushed its competitors (VW, MB). When the current Mustang was new, it sold 192,000 units. and Mustang is not even a bread and butter car. Mustang doesn't get freshened up anywhere near as frequently as the BMW.
Ford and GM are just too big.