i-ELOOP is a system that uses a capacitor to store electricity from the alternator, which is controlled so that it generates electricity mostly during deceleration.
So this is a regen system which runs from the belt driven alternator, and the small amount of energy it captures is used not to move the car but only to recharge the battery and run the electrical system.
This isn't hybridization, it is just alternator duty cycle optimization. It won't save much fuel, maybe 3-5%, but on the other hand, it won't cost or weigh much either.
The big fuel economy savings are when you store lots of energy from braking in a battery or super-capacitor, and then use that power to re-accelerate the car. Mazda, however, isn't up to making the investment, apparently.