The Volkswagen twin up! Plug-in Hybrid Concept, unveiled at the Tokyo Motor Show, has an official fuel economy figure of 256.8mpg and 27g/km CO2 emissions.
The twin up! concept car uses a 0.8-litre two-cylinder turbodiesel engine in series with a 27 kW electric motor and a seven-speed DSG gearbox – a version of the drivetrain found in the pioneering XL1.
All new Volkswagen vehicles are deigned to accept alternative power trains as well as conventional ones, so only minor modifications (such as lengthening the front overhang by 30 mm) were necessary to fit the plug-in hybrid drivetrain into the four-seat twin up!.
The twin up!’s diesel engine and electric motor each produce up to 35 kW, while the maximum system power output of the twin up!’s front-mounted drivetrain is 55 kW. 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.
Good aerodynamics (0.30 Cd), a low unladen weight (1,205 kg) despite the addition of the lithium-ion batteries, and 165/65 R15 tyres optimised for low rolling resistance all help to maximise the twin up!’s efficiency, and to achieve the 256.8 mpg combined fuel consumption figure and 27 g/km CO 2 emissions.
A decoupling clutch between the diesel and electric motors allows the electric motor to operate independently. Provided that there is sufficient battery charge, the driver can press the e-mode button for emissions-free driving.
On electric power alone the twin up! can operate at speeds of 77 mph, and accelerate from zero to 37 mph in 8.8 seconds. The range on batteries alone is up to 31 miles. Using diesel and electric motors together, the car can accelerate from zero to 62 mph in 15.7 seconds, and on to a top speed of 87 mph. Combined torque peaks at 215 Nm.
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.