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Volkswagen Unveils New One-Liter Concept Car; Smallest Production-Intent Diesel Yet from Volkswagen Applied in A Full Hybrid Design

Dr. Ulrich Hackenberg, Member of the Board of Volkswagen Brand Technical Development, in front of the Volkswagen Concept Car L1 in Frankfurt. Click to enlarge.

Volkswagen unveiled the L1, its second-generation one-liter class concept car, at the Frankfurt Motor Show. The diesel-electric full-hybrid vehicle, weighing just 380 kilograms (838 lbs), offers an initial glimpse at how a future production version might appear.

The “one-liter” designation refers to the design target of fuel consumption of 1 liter per 100 kilometers (235 mpg US). Volkswagen first revealed a one-liter concept at the annual meeting in 2002, then cancelled the project in 2005. (Earlier post.) In 2007, Volkswagen CEO Martin Winterkorn confirmed that VW was resurrecting the 1-liter car project and would place it in production. (Earlier post.)

The earlier, first-generation 1-Litre concept. Click to enlarge.

The L1 combines a two-cylinder 0.8L TDI (the smallest diesel engine intended for production applications ever built by Volkswagen); a 10 kW motor; and 7-speed DSG installed at the rear. As a unit, they represent the most fuel efficient hybrid drive in the world, according to Volkswagen. The aerodynamic (Cd = 0.195) L1 offers combined cycle fuel consumption of 1.38 L/100km (170 mpg US), with CO2 emissions of 36 g/km. Top speed is 160 km/h (99 mph).

0.8L TDI. In the standard ECO mode, the 800 cm3 TDI develops a power of 20 kW / 27 hp (at 4,000 rpm); in Sport mode—used to reach the car’s top speed, for example—the car’s power increases to 29 kW / 39 hp (at 4,000 rpm). The maximum torque of the TDI is 100 N·m / 74 lb-ft (at 1,900 rpm). The L1 also has a Stop-Start system, which automatically shuts off the drive unit when the vehicle is at a stop and restarts it when the gas or E-pedal is pressed.

The two-cylinder 0.8-liter TDI unit has been derived from the 1.6 TDI just introduced a few months ago. The 1.6 TDI is making its debut at the IAA in cars such as the new version of the Golf BlueMotion (3.8 l/100 km) and the Passat BlueMotion (4.4 l/100 km). (Earlier post.)

Based on their common origins, the 0.8 TDI and 1.6 TDI have identical cylinder spacing (88 millimeters), bore (79.5 millimeters) and stroke (80.5 millimeters). These TDI engines also share key internal engine features for reducing emissions. They include special piston crowns, multi-injection and individual orientations of the specific injection jets. On both drivetrains there is exhaust gas recirculation, an oxidation catalytic converter and a diesel particulate filter. Equipped this way, the TDIs in each Volkswagen fulfil the limits of the Euro-5 emissions standard.

The 1.6 TDI, thanks to its common rail injection, is also an exceptionally quiet and low-vibration diesel engine. These positive properties have been successfully transferred to the two-cylinder unit. The TDI’s aluminium crankcase was also constructed with high precision to achieve very low friction losses. The oil pump, designed to operate at a maximum oil pressure of 4.0 bar, also contributes to engine efficiency.

Another example of how the entire drive system is configured for high efficiency is the L1’s cooling system. Its external water pump is controlled by engine management so that cooling is only activated while engine operating conditions require it. This thermal management also contributes to reduced fuel consumption. A second electric water pump, also activated only when needed, provides cooling required for the starter generator and the power electronics in a separate water circulation loop operating at a lower temperature level.

The E-motor. The hybrid module has been integrated into the housing of the 7-speed DSG (Direct Shift Gearbox). It is located between the TDI engine and the DSG gearbox and consists of a 10 kW / 14 hp electric motor and a clutch. The E-motor is supplied with energy from a lithium-ion battery located at the front of the car. An electronic power control module, operating at around 130 volts manages the flow of high voltage energy the battery and to the E-motor. In parallel, the vehicle’s low voltage electrical system is supplied with the necessary 12 Volts through a DC/DC converter.

In normal operation the electric motor can support the TDI engine in conditions such as by electronic load point shifting and in acceleration. If necessary—generally during acceleration—the E-motor can supply 40% additional torque over the entire speed engine speed range. The E-motor can also propel the L1 over short distances by itself. In this case, an auxiliary clutch decouples the TDI from the drivetrain.

Restarting the TDI is a very easy process. In so-called “pulse starting” of the TDI, the electric motor is sped up and is then coupled to the TDI unit to provide almost instant starting. The entire process takes place automatically and without jolts, so the driver hardly notices the restarting of the TDI engine.

In braking phases, the E-motor operates as a generator to charge the lithium-ion battery by recovering braking energy. The gears of the automatically shifting DSG are always selected with the aim of achieving the best possible fuel economy. The engine controller regulates all energy flow and drive management tasks taking into account the moment by moment demands for power made by the driver. Some of the parameters used to calculate the optimum propulsion mode for the given conditions are: accelerator pedal position, engine load, momentary fuel demand, energy supply and the mix of kinetic and electrical energy at any given time.

Transmission. Gear shifting work aboard the L1 is handled by the 7-speed DSG. Compared to the version equipping the new Polo, the design of the L1 Direct Shift Gearbox has been developed to include clutch control for the hybrid module. Furthermore, individual gear ratios have been optimized to attain responsive driving performance despite the car’s extremely low fuel consumption. The hybrid module is located where the flywheel is usually to be found.

Body. The dimensions of the L1 are distinctive. While the length of the L1 at 3,813 millimeters is still similar to that of a Volkswagen Fox, and its height of 1,143 millimeters nearly matches that of a Lamborghini Murciélago, the car’s aerodynamically optimized narrow width (1,200 millimeters) has no comparisons in the world of today’s production cars.

The two-seat monocoque, including the tubular frame driver’s seat and passenger seat as well as the exterior body skin, all consist of carbon fibre reinforced plastic (CFRP). There are no doors. Instead, the driver and passenger climb into the L1 from the top. An electrically actuated entry canopy above the seats is opened and closed for this purpose.

Headlights and taillights all utilize LED technology. The rear wheels are completely covered; their wheel covers can be removed to change the Michelin low resistance tires. The underbody is also completely enclosed. The 0.8 TDI is cooled via adaptive air channels integrated in the sides of the car body. These automatically open and close based on the hybrid unit’s operating state and vehicle speed. The tailgate is opened in the usual, manual way. It too consists of CFRP. Inside is a stowage space of 50 liters.

Of the 380 kilograms curb weight, 122 kg are taken by the drivetrain, 79 kg by the chassis, 35 kg by interior furnishings and 20 kg by the electrical system. The remaining 124 kg is the weight of the body.

These 124 kilograms can be further broken down: 64 kg are accounted for by the CFRP monocoque including integrated passenger seat; 28 kg is the weight of the entire CFRP exterior skin; 19 kg for the CFRP entry canopy; 9 kg for the CFRP driver’s seat; and 4 kg for the LED lights.


The Goracle


Incredible mileage! Although I'm afraid that our lord, Algore, has expanded his carbon footprint to the point where he will not be able to fit in this vehicle. This must be corrected.

Praise be to Algore!


Mick the Economist

I understand that Goracle doesn't acknowledge the theretical possibility of catastrophic climate destabilization. What I don't understand is why (s)he thinks climate change denialism is relevant to every post on this site. This is just a cool concept car; it's nothing to do with climate change.

Will S

When the day comes that Goracle stops trolling, engage him. Until then, don't feed him.

I've been tracking this car for years now and look forward to its debut. The price may be the sticking point, however; it will be produced in a prototype shop in low numbers.

Roger Pham

Finally, a two-cylinder diesel that Henry Gibson and Lucas would approve...but sorry, Henry, still not an OPOC...but getting closer.

I'll be really happy if VW would offer a version that can run on Hydrogen, either compressed or adsorbed. Only 1 kg of Hydrogen will be needed, given the tremendously efficient engine. Otherwise, I concur with The Goracle: Not green enough for me, either.

Praise be to Algore!

Nick Lyons

Cool car--could be a fantastic commuter. I do wonder how you get into the car in a downpour without drenching the interior, however.

Will S



This is the car GM should have been selling ten years ago.

I'll bet VW has a waiting list until the competition catches up.


What's old is new again. The Germans have reintoduced an update version of the Messerschmitt KR-200


I'm just a little bit disappointed with this car[but ONLY a little bit]. They bill it as a 'one litre car'[100km/litre] but that's wishfull thinking.

The prototype got 235 mpg US with a pure diesel drivetrain while this "hybrid" gets only 170 mpg. Yeah I know that's still a heck of a lot and I should be happy but the prototype spoiled me. They just gave up too much for the mass-market bells&whistles; with all the press about hybrids and PHEVs you'd think it should have gotten at least as good mileage as the prototype.

Henry Gibson

I had to go look up what a TDI unit is. TURBO-CHARGED-DIRECT-INJECTION engine. VolksWagen TDI or Ford Mustang are both just now brand names. The Largest engine in the world is supercharged direct injection. Yes two cylinders is enough for most cars. They are talking about the engine as though it is always producing 39 hp. At best efficiency, 29 kw requires more than three gallons of fuel an hour. This engine is far more than big enough for a range extender for a TESLA. It is also big enough for a series-plug-in-hybrid Ford 350 pickup truck for most of the miles put on those trucks.

More engineering time went into this car than in the first five years of Volkswagen. ..HG..

Thomas Pedersen

What an absolutely fantastic commuter car!!!

I love that it's a hybrid, although with emphasis on running on diesel. The load point shifting by small drain on the batteries is a brilliant way of saving a lot of fuel - by the synergy of relieving the engine and be able to run in higher gear.

The engine thermal management is great way of reducing particulate pollution. I hope that using the E-motor for increased acceleration will reduce the pedel-to-the-floor-cloud-of-smoke that all diesels (including mine) suffer from.

Only thing is, I expect this car to be quite expensive, as all diesel hybrids most likely will be. The all-new developed gearbox does not help this point. On the other hand, I would not be surprised if VW will sell this car at low margin or possibly slight loss to corner the market, lower their fleet CO2 emission and as a prestige project.

The fact remains that this car will have extremely low marginal cost per mile as a long-distance commuter car. And here in Europe where we are not as afraid of diesels, there is less risk of being completely obliterated by Hummers... In that regard, not that without doors, the (essentially monocouque) body will be extremely strong. But it does not help with the momentum transfer in a crash, though...

It will be a long time before any EV can match the 36 g CO2/km with power from the grid and several hundred mile range!


I'd be curious to see this car with Cyclone engine. No need for a gearbox, no need for the hybrid unit, and no need for any cats or other emissions equipment. Power density of the cyclone is 2x that of a traditional NA gasoline engine. Overall efficiency may drop as the cyclone is only 33% efficient vs. the diesel engine in this concept which is likely 42% efficient but most of that would likely be made up by the reduced weight and reduced drivetrain losses.


BTW, I'd be willing to bet that this vehicle is actually very safe.


Why not make it a 3 wheeler?

It would be cheaper, lighter, and even less safe.


It is not expensive.

It is a "concept car, . . . offers an initial glimpse at how a future production version might appear."


I woule lov eto have a 2 seat in tandem instead of a 4 seats car that I don't need.

At least it has 4 wheels so it can't be denied the right to be a "car" and be entitled to gvt subsiies for development


Why not make it a 3 wheeler?
It would be cheaper, lighter, and even less safe.

Three wheelers can be very stable as long as the front wheels are far enough apart. But that would have given this car more frontal area (and drag). To make a car this narrow and still be stable you need to have four wheels and a low centre of gravity, or build it so it can lean into a turn.


More than enough to drive to work and back. Who needs a Hummer I, II or III (or equivalent ICE monster) to drive around, if a 838 lbs hybrid can do the job?


The current 4 seats could be replaced with 2 oversized seats for the American model.



So you want to turn your four seater into a two seat tandem? Check out what this guy did-


@ai_vin I am responding to your post from September 15, 2009 at 03:37 PM

In germany we had the 3L car (that's not displacement it is fuel consumed per 100km) that's the formula to get mpg from Liters per 100km: 100km/1.61/Liters*3.785=78mpg (10 years ago in a 5 seater)
that was the 3L VW Lupo and the Audi A2 3L. both TDI but never sold in the united states of america. they must have banned these TDI's for some reason.
Volkswagen never wanted to build the hybrid car because they said years ago in a press release that they can build more efficent cars without the extra weight of a hybrid. for some reason they mess arround with it now. maybe that's a requirement to get into the US market.
That might be the reason why the L1 does 235 miles per US gallon with just the diesel engine and only 170mpg as a hybrid. so maybe hybrid is not so good as Toyota wants us to believe.
I have the suspicion that the US government has an import ban or extremly high taxes on the TDI's.
Also a reason could be that Toyota has such a strong lobby in the united states and might have something to say or some kind of deal with the US what cars can get shipped in here.
but I am just guessing, maybe someone has more founded information about why there were no german 78mpg in the US 10 years ago.

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