Of course I'm not very glad when I'm lower than 30 mpg espacially because the price of the fuel is expensive in Europe (I pay about 35$ to fill the tank of my 240D)!!
In Europe, we can find a lot of diesel engines due to the very
important amount of tax we have on the fuel. For example, in France, the price of gasoline is about 3.5$/gallon and 2.5$/gallon for the diesel.
The lower level of tax on the diesel has largely contributed to develop the sell of the diesel powered cars (Presently, about 60% of the cars sold in France are diesel powered against 15% 20 years before).

But now, new problems appear : lot of scientic studies have proved that the particles released by the diesel engines are dangerous for the health and can lead to a cancer. So, there are presently a lot of developements in Europe in order to remove those particles. Peugeot is curently the only one on the market to sell cars equiped with a particles filter (the FAP = Filtre a Particules) on the HDIs engines (the equivalent of the CDIs engines)

But it is likely that due to more and more strict laws regarding the pollution generated by the diesel engines their futur is not assured.

__________________
in France : 240D 1981 380 000 km
240D 1984 252 000 km
300D 1978 325 000 km
in the US : Ford Tempo 1993 70K