Just saw the first stations with 0.99€/litre (roughly 3.80$/gallon) for diesel today.
Never been to Austria, but I lived in Germany for a year, and I worked in the Netherlands for a semester. What I noticed there was that Diesel was cheaper than gasoline. It was weird. I assume that this is also the case in Austria. (?)
On the other hand, here in the United States, Diesel is always more expensive than regular auto fuel. Typically, Diesel costs about 35c per gallon more than regular. For example, right now, near me, the fuel sells for about $2.13, and the Diesel sells for about $2.44.