46.2 from a normally aspirated Ford engine and auto gearbox sounds good to me, but mpg is much more affected by the speed you set on cruise or drive. i.e., do you cruise at 50 mph or 90 mph.
I think if you drive at 70, whether that is with or without cruise, the mpg would broadly be the same.
Most people who complain about the economy are doing a lot of town and city driving where the autobox is spending a lot of time in low gears and is constantly accelerating and decellerating or simply doing a lot of short yrips where the engine hardly warms up.
If you want real economy, then ditch the auto box and buy a diesel. That said, i am currently averaging 44 mpg on my 1.0 123 bhp b max.