You people realize that besides the US and Arab oil states, in the rest of the world you pay some serious money for fuel, right?
So yeah, for all the normal people that don't care for crazy quick cars or have rich parents, the obvious choice for an A-to-B car is a diesel. If you drive a lot it can pretty much cut your fuel costs in half.
Price for petrol and diesel in most of Europe is hovering around a euro+ per liter, so yeah, fuel economy is interesting over here.
As far as diesel performance goes, it's getting better obviously. It'll never surpass petrol for the reasons Deez stated, but it's interesting stuff nonetheless.
They're making a TDI R8, so yeah. V10 500 horsepower and enough torque to rotate the moon,.