As with the 500, the 500C's current 1.4 litre four-cylinder engine will be ousted in favour of the two-cylinder 875cc TwinAir unit.
Halving the engine's cylinder count does the car little harm however, with the new engine offering more torque and improved fuel economy.
Power for the turbocharged TwinAir engine is rated at 63kW and 145Nm, meaning output is down by 11kW but torque is up by 14Nm. The 500's 0-100km time is little changed, moving from 10.5 seconds to 11 seconds.
The big win is in fuel economy, falling from 6.1 l/100km for the 1.4 litre four-cylinder, to 4.1 l/100km for the new TwinAir.
The new engine will also push the 500 twins to the top end of Australia's green car list, beating all-comers in the petrol market and matching the fuel consumption figures of the Lexus CT 200h hybrid hatch.
Pricing for the upgraded 500 hardtop and 500C convertible has yet to be revealed, but don't expect the numbers to stray too far either side of the current line-up - $24,990 and $28,990 respectively.