Smart adds start-stop technology
The cars have stop-start technology that cuts the engine when the car is travelling at less than 5mph and the driver is braking - saving fuel and lowering emissions.
The coupe is available with either a 60bhp or 70bhp engine, while the cabriolet has only the 70bhp engine.
Fuel savings over the standard models are up to 24%. The coupe will average 65.7mpg and emit 103g/km of CO2.
The cars have also been given mild face-lifts, including a redesigned instrument cluster and new net storage pockets in the driver and passenger doors.
The mhd models are available in three trim levels: pure, pulse and passion. Prices start from £7060.