Don’t get confused with ‘mild hybrids’
What is a mild hybrid system?
It's a relatively inexpensive and fairly simple technology that reduces the fuel consumption and CO2 emissions of petrol and diesel-engined cars. Generally, it involves a small electric generator that replaces the traditional starter motor and alternator (the device that keeps the 12-volt battery charged), plus a small lithium-ion battery.
Most mild hybrids run on a 48-volt electrical system – a higher voltage than the electrical systems of traditional combustion engines use. The 48V system powers components that would have previously been powered by the engine, enabling it to operate more efficiently.
How do mild hybrids work?
As the name suggests, a mild hybrid system offers only gentle electrical assistance to the engine – not enough for the car to drive on electric power alone. The systems work in slightly different ways from brand to brand, but in general, they assist the engine under hard acceleration and help make its stop-start system smoother in operation.
Such systems can also harvest energy when the brakes are applied, converting it into electricity that's fed to the lithium-ion battery to provide extra assistance when it's needed. On average, a car with mild hybrid technology is said to be up to 15% more efficient than its conventional counterpart.
Source What Car
You know it makes sense! 
