I'm just gonna go ahead and say it's probably
NOT worth it. It basically looks like GM's hybrid system on the Saturn Aura and all it's clones.
Essentially an alternator and battery on steroids.
Just for laughs, the Saturn Aura base I-4 gets 22mpg city/30mpg highway.
At $4000 more, the Saturn Aura Hybrid I-4 gets 24mpg city/32mpg highway, and it has 5 fewer horsepower and 1 fewer ft-lbs of torque.
That's gonna take an awfully long time to pay for itself.