They made a a 2.2i auto but I don't think its anymore fuel efficient than the 3.0i.
My 3.0i auto has done 34mpg over 78 miles on an economy run using the fuel pump to measure rather than the on board computer. I had to drive like a Saint and never drove like that again.
The 3.0i and 3.0si manual cars seem to get closer to 40mpg on the motorway.