I'd go with a diesel. In Europe we get the 40d, which unfortunately you don't have in the US. It is by far the best option for Europe with those crazy fuel pri es. I had a 4.8 and got 12-13 mpg for city driving. I get 18 mpg for my 40d.
Acceleration is better on v8 if you rev it up, otherwise its quite comparable.

Still you US guys are lucky. Here I have to pay USD 6.65 per gallon of premium diesel/gas and had to cough up 130k USD for my X