the modern 8 speed auto, has been programmed to lock up as early as possible, has quicker shifts than the previous generation and a pretty good torque converter. As well as having more ratios to choose from. In most cases the modern autos are more fuel efficient than the manual.
Yes you "could" get better economy from the manual, but you'd need to be thinking about it constantly and driving with your attention more on the economy than actually being safe on the road. These days the auto is almost a no brainer.