problem with turbo engines is that if you treat them like a 'normal' engine and when you stop the car you turn ignition off straight away you can wreck the turbo, you have to keep engine ticking over and let turbo spool down and cool down for a while - how may people are gonna remember to do that every time, eg. - when the kids are in the back bouncing around.
also lots of people out there really disappointed with mpg they are getting from ecoboost engines