Volvo has chosen the Geneva show to reveal the 149mpg hybrid V60 estate that is scheduled to go on sale towards the end of next year.
With the capability to cover up to 31 miles on electric power alone, its official CO2 figure will be just 49g/km way below any other car with an internal combustion engine.
The hybrid is based on the most powerful D5 five-cylinder diesel V60, but it also has a rear-mounted electric motor to give a power boost and all-wheel-drive capability when needed.
Volvo chose the V60 as the basis for its first hybrid because the impact on luggage space is less marked with an estate than with a saloon. A little over a quarter of the standard boot is lost by the need to raise the luggage deck to make space for the electric motor and batteries.
The decision to go down the more complicated route of making a diesel hybrid rather than one with a petrol engine was taken to maintain the standard 1800kg towing capacity. Volvo claims the hybrid V60 will be able to accommodate five people and still carry 80kg of luggage.
The diesel engine develops 215bhp and 325lb ft of torque, but the electric motor can boost this by a further 70bhp and 148lb ft.
Three operating modes
The car gives drivers the choice of three operating modes.
HybridThis is the default setting, in which electric drive will be the dominant source of energy, with the diesel cutting in only when extra power is needed or battery power is getting depleted.
Pure activates all-electric running, although the diesel will help out when necessary, such as when kicking down to overtake.
Power mode switches on the diesel engine and makes the motor available as an extra power source.
Drivers will be able to turn on the electronic all-wheel-drive system in all three modes to increase traction in slippery conditions, and it will function even if the battery is flat by drawing power from an on-board generator.
Volvo claims an overall range of up to 750 miles, a top speed of 125mph (62mph in all-electric mode) and 0-62mph acceleration in 6.9 seconds. A full recharge of the battery will take around 4.5 hours through a 240-volt domestic socket.