As has been said, the biggest chunk of it is taxes. Presuming that the producers charge European nations the same as they do the US, I do find it interesting that the prices are so much higher there. That much more tax or that much more profit for the gasolene companies?

I paid $22.50 to fill up my car this afternoon, at $1.52 per gallon, and I shudder to think of what it would cost in the UK. I do drive a small SUV (that gets about 25 miles to the gallon), and I do need (or at least appreciate) all of its features from time to time, but I also expect I'd find ways to cope if a tank full cost me two or three times as much. That really is the only way to get the behemoths off the road...make people pay through the nose to drive them.