[euromodder]

When the higher energy content of diesel is taken into account, the numbers aren't that good anymore.
Then there's the matter of the worse emissions: NOx, particulates.

The sheer complexity of today's diesels is another problem area.
I'm not the only one with particulate filter issues.
Current research indicates that having a DPF may well be worse than having none - the particules are still there, but smaller and more harmful as a result.