Regarding fuel efficiency:
"And the A380?s environmental friendliness does not stop at noise reductions. The economic fuel consumption of the A380 ? around 13 per cent lower fuel burn than its closest competitor ? will also help reduce the impact of exhaust gases on the atmosphere. Indeed, the A380 will be the first long-haul aircraft to consume less than three litres of fuel per passenger over 100 kilometres (95 miles per imperial gallon) ? a fuel burn comparable with the best of small modern turbo-diesel cars."
http://www.aviationboom.com/features/feature_A380.shtml