This may also have to do with your new vehicle more than anything else.
You didn't mention what your previous one is but did mention your new one is a Cruze. Especially if you purchased the ECO model than this may be the case.
Chevy is trying to squeeze every MPG they can out of this car, such as on the ECO manual having an "ECO overdrive gear" (just a taller gear to keep the RPMs lower when crusing on the highway).
The more commonly known items related to fuel mileage are size of the engine and weight of the vehicle.
Aerodynamics have a big play to, the more wind resistance (drag), the more work the engine has to do.
Another is rolling resistance, some tires are rated as "low rolling resistance".
All of these items to reduce fuel consumption are going to also make the feel of engine braking less as the car will coast easier on its own.
Engine braking works a lot better on a vehicle that wants to slow down on its own and so needs the engine pushing it forward to keep going.
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Well, again with the Eco stuff, maybe they are doing something odd.
Engine braking happens because when you let off the gas pedal at speed the car makes the choice to provide 0 fuel to the engine allowing the engine to be rotated by the rotation of the tires, unlike when stopped and you release the gas pedal it maintains an idle.
Maybe Chevy has something where the Eco still provides some fuel and continues to fire. Since consistency is one of the most important things to good fuel mileage, they may have found that normal engine braking for a standard driver was more of a hindrance.
That is all just wild guessing, I haven't read anything on that but I could see there being something behind better fuel mileage by having the vehicle better maintain its own speed and requiring the input of the brake pedal to do the stopping.
It seems like the general driver is mostly always on the gas pedal or the brake, they don't know anything else.