The only point in the scenario where the car " recycles" energy is during the deceleration... fuel is still being spent at this point and because it is largely unnecessary and only happening to prevent the engine stalling.... the energy from this is used as a short charge to the battery, which is then spent moving the car forwards again up to 20klm ph... thats if you come to a dead stop, otherwise its fuel that drives you.

Figures of 4.4 ltrs fuel to 100klm is such a variable due to driving conditions. It would be better to quote its worst performance and its best ( 4.4) and then an average would be pretty much what you would experience.
In my ute, if i do 100klm at 100klm ph without speeding up or down, but a straight cruise my fuel efficiency leaps upwards... its the speed up from speed down that kills any figures.

I agree Brett.. it will save you $$ on fuel... how much it saves you over time against increased cost only time can tell