Makes as much sense as eating at McDonalds because it's cheaper; what about the quality of the drive during those years? There's more to the decision than pure economics in my opinion. If so, I am positive a VW diesel will cost less or even one of the over 40 mpg vehicles Ford offers.

If the decision of what to drive is purely based on monetary considerations, I am sure used vehicles will also come out better, just not a BMW.