While Volkswagen introduced XL1, the world’s most fuel efficient production automobile, at the Frankfurt Motor Show, it saved an event thriftier car for the Tokyo show. The newcomer, coming from under the wraps at the Tokyo Motor Show, is the Volkswagen twin up! Despite the annoying lowercase/punctuation mark name, the twin up! shows how relatively mundane technology can be combined for extraordinary results. The twin up! has a two-cylinder diesel engine with plug-in hybrid power system.
And it’s not all that different from the production up! model, a four-place, four-door microcar. The only significant exterior difference between the twin up! concept and its production equivalent is the front end elongated by 1.2 inches, which is to say, not a lot. It’s what’s inside that count, as the saying goes, and that’s substantial.
The two-cylinder diesel is essentially a 1.8-liter four-cylinder TDI cut in half, resulting in a 0.8-liter engine rated at 47 horsepower. The clean diesel twin’s output is matched by that of an electric motor for a total peak power rating of 75 horsepower.
Details for reducing emissions include special pistons with recesses for multiple injection, and individual orientation of the injection jets. An exhaust gas recirculation system, an oxidation catalytic converter, and a diesel particulate filter are also used to reduce tailpipe emissions
Two cylinder engines are notorious for the shakes—ask any twin-cylinder motorcycle rider—but the VW turbo two has a balance shaft that turns at the same speed as the crankshaft.
The hybrid’s electric motor is between the engine and the Volkswagen twin up!’s seven-speed DSG transmission, positioned where the flywheel would usually be, sharing the space with a clutch.
The electric motor gets its electricity from an 8.6 kWh lithium-ion battery located in the back of the car. For the tech savvy, the power electronics, operating at 308 Volts, is at the back of the car, as is the manage the flow of high-voltage energy between the battery and the electric motor and convert direct current to alternating current. Also at the back of the car, also under the trunk, are the 12-volt battery for the chassis electrical system, and an 8.7-gallon fuel tank.
The plug-in hybrid Volkswagen twin up! can go up to 31 miles on electric power alone and can hit a top speed of 78 mph, thought the latter would significantly reduce the former. The hybrid system can declutch the motor from the engine upstream from it, sending power through the seven-speed DSG transmission. The twin up! can operate in full-electric motor automatically, or when the driver has the e-mode button pushed.
In the “New European Driving Cycle” — the standard testing and comparison driving cycle for plug-in hybrid vehicles in Europe — the Volkswagen twin up! achieves a remarkably low fuel consumption of 214 mpg. It’s not all drivetrain, as good aerodynamics (0.30 Cd), light weight overall (2657 lbs) with lightweight plug-in drive components, and low rolling resistance 165/65 R15 tires all contribute.
Performance hardly overwhelms, putting it mildly. In full-electric mode, the twin up! can go from 0 to 37 mph in 8.8 seconds—by when most cars are reaching 60 mph. In hybrid mode, reaching 62 mph takes a relatively glacial 15.7 seconds, and waiting long enough rewards with a top speed of 87 mph.
Volkswagen claims that developing the twin up! wasn’t difficult, as all new Volkswagen models are built to accommodate hybrid powertrains, as with the Jetta Hybrid we recently tested.
But don’t expect the Volkswagen up! in the U.S. any time soon, as the market is questionable for a vehicle that small, and anyway, the up! would have to be adapted to EPA and NHTSA rules, go through the testing and all the other things that make bringing a Eurospec model over here expensive.
And while it would be possible to build, for example, a Jetta TDI Hybrid, the expense of a diesel engine and hybrid powertrain would push the purchase price well above what most would be willing to pay for a Jetta.
If the Volkswagen twin up! makes it from concept to production, we foresee a Europe-only limited-production model. But we could be wrong.