Audi is testing a supplemental 48-volt electric system in two prototype vehicles – modified mild-hybrid versions of the A6 TDI and the RS 5 TDI – in order to add in more electric technology ...

And it will preview new 48-volt hybrid technology coming to future Mercedes ... with an integrated 27-hp electric motor and inverter that draws power from a 1.3-kilowatt-hour lithium-ion battery.

The venerable Fiat 500 is expected to ditch its 1.3-litre MultiJet diesel engine in favour of cleaner 48-volt hybrid technology when the new model is revealed before the end of the decade.