>> Supposedly the car operates as a 4-cylinder until put in pursuit mode, at which point the other 4 cylinders kicks in.
The feature has been available on some Chrysler hemi engines for a couple of years. The engine computer basically shuts off fuel injection and firing to 4 cylinders when sensors indicate the vehicle can maintain speed with minimal energy expenditure.
The shut-off can occur when maintaining speed on the interstate, or on the back road. All eight cylinders will kick in when trying to accelerate, whether on an incline, to pass someone, or from a stopped position.
The purpose of the feature is simply to decrease overal fuel comsumption, which is good for both the vehicle owner, and Chrysler in achieving its corporate fuel consumption requirements with the EPA.
General Motors has a similar fuel reduction feature on some of its engines, and I believe it was the first U.S. car maker to offer this feature ... maybe 15-20 years ago ... on some Cadillacs. At that time, I managed car care facilities for Exxon, and that engine was a techno loser. It was always safer to refer customers with problems involving that engine back to the dealer.