Diesel Dodge Dart Concept

I dont think you will get any of that easy, you won't get 40 mpg, you won't get under 3000 pounds, you won't make 300 hp. You will spend over $20,000, you will never get your money back, you will never actually save money compared to what you spent.
If you want it to be exactly the car you always wanted, to be outside the box, then I'm all for it. But this thread always seemed about doing something to save money. Buying a diesel might do that in certain situations (although I argue 90% of them never will just like hybrids) but building your own diesel conversion never will actually save money.