Maybe I'm dumb and did the math wrong, but isnt 2.90Euros/Liter about ~$1.15/gal US?
I think you've done it completely wrong. €2.9 equates to $4.16US so thats $4.16/litre. Then there's 3.785 litres to a US gallon - $15.78. That's more than what we pay in England but the roads over in Germany are way better.