According to wikipedia,
fuel taxes in Germany are €0.4704 per litre for ultra-low sulphur Diesel and €0.6545 per litre for conventional unleaded petrol, plus Value Added Tax (19%) on the fuel itself and the Fuel Tax.
1 US gallon happens to equal 3.78541178 litres. With an exchange rate of 1 Euro = 1.3949 U.S. dollars, this results in a fuel tax (not including the V.A.T.) of $2.4838(3943) / $3.4559(373) per gallon for diesel/unleaded fuel.