So how many of these cars have turbos? I know the BMWs at least are mostly turbo 4-cylinders.

The whole reason manufacturers are moving to small displacement turbocharged engines over large displacement naturally aspirated engines is because the EPA MPG tests never run the engine in a range where the turbo is doing much. Put the car in the real world and the driver's lead foot makes the turbo kick in, killing fuel economy.

Ref: http://autoweek.com/article/car-news/mpg-or-performance-its-...