Volkswagen has unveiled a hybrid version of its up! city car called the twin-up! at the Tokyo Motor Show.

The twin up! concept uses a 0.8-litre two-cylinder turbodiesel and a 27 kW electric motor and a seven-speed DSG gearbox for a combined power output of 75 horsepower, while offering an amazing fuel consumption of 256.8 mpg with CO2 emissions of 27g/km.

The modified drivetrain is from a pioneering XL1.

According to Volkswagen all their new vehicles are designed to accept alternative power trains as well as conventional ones, so all that was needed to fit the new drivetrain was the lengthening the front overhang by 30 mm.

The 8.6 kWh lithium-ion battery pack, 12 V battery and 33-litre fuel tank are all located between the rear seats and the boot.

Weighing 1,205kg, the twin-up! concept rides on 165/65 R15 tyres optimised for low rolling resistance.

A decoupling clutch between the diesel and electric motors allows the electric motor to operate independently at speeds of 77 mph, and accelerate from 0-37mph in 8.8 seconds. The range from a full battery is up to 31 miles.

With both engines working, 0-62mph comes in 15.7 seconds and the top speed is 87mph. Not very fast, but lets not forget the average fuel consumption is 256.8 mpg!

When braking, the electric motor acts as a generator, and the braking energy is used to charge the battery. Under appropriate conditions the TDI engine can be used to charge the main traction battery.

Externally, the twin up! is distinguished from the standard model with flowing blue double stripes above the sills, ‘Sparkling White’ exterior colour with blue flakes, while the interior features off-white ‘Ceramic’ colour and a bespoke instrument panel.

Volkswagen has unveiled a hybrid version of the up! city car at the Tokyo Motor Show. The twin up! concept uses a modified version of the XL1’s diesel-electric drivetrain and is said to return an incredible 257mpg.

The twin up! concept is based on a plug-in hybrid system, which combines a 0.8-litre two-cylinder turbodiesel engine, with a 27kW electric motor. Power is delivered to the front-wheels through a seven-speed DSG gearbox and top speed will be 87mph. However, acceleration will not be impressive, with official figures saying 0-62mph will take a zimmer frame rattling 15.7 seconds.

On battery power alone, the twin up! can cover a range of 31 miles, thanks to a 8.6 kWh lithium-ion battery pack that is positioned between the rear seats and the boot.

Combined torque peaks at 215Nm, while CO2 emissions are just 27g/km, which makes the twin up! exempt from London’s Congestion Charge.

Volkswagen tells us it will be simple to select power modes, with an ‘e-mode’ button on hand for the driver to decouple the clutch between the diesel and electric motors. The electric motor can also act as a generator under braking to charge the battery, while the 800cc TDI engine will ‘under the right conditions’ be able to replenish the main traction battery.

The engineers that built this little car say it was relatively easy to modify the chassis to accept the hybrid system, but no information has been given regarding price or production dates. However, industry insiders claim that the twin up! will most likely follow on from the XL1, which will reach showrooms in 2014.