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Volkswagen to unveil 261 mpg XL1 prototype in Qatar

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January 25, 2011

The Volkswagen XL1 protoype

The Volkswagen XL1 protoype

Image Gallery (19 images)

At the dawn of the millennium, Prof. Dr. Ferdinand Piëch, who is today Chairman of the Supervisory Board of Volkswagen AG, set his sights on creating a practical everyday use production car with a fuel consumption of 1.0 liter per 100 km (235 mpg). In 2002 a prototype VW 1-Litre was unveiled, which was followed in 2009 by the second-generation model, dubbed the L1, which boasted a combined diesel fuel consumption figure of 1.38-liter/100 km (170 mpg). As impressive as that figure is, the company has now managed to squeeze a combined fuel consumption of just 0.9-liter/100 km (261 mpg) with its third-generation VW 1-Litre prototype – the XL1.

With a combined fuel consumption of just 0.9-liter/100 km and CO2 emissions of 24 g/km, VW is calling the XL1 is the most efficient car in the world. This is achieved through a combination of lightweight construction using monocoque and add-on parts made of carbon fiber, very low aerodynamic drag (Cd 0.186) and a plug-in hybrid system consisting of a two cylinder TDI engine (35 kW/48 PS), E-motor (20 kW/27 PS), 7-speed dual clutch transmission (DSG) and lithium ion battery.

Keeping the weight off

With a weight of just 1,753 lb (795 kg), the car also takes advantage of progresses made in Formula 1 car construction in the manufacture of body parts from carbon fiber reinforced polymer (CFRP) parts. Together with suppliers, VW has developed an patented a new system for CFRP production known as the advanced Resin Transfer Moulding (aRTM) process that has allowed the company to achieve significant reductions in production costs, which it says is an important step towards making a limited production run of the XL1 viable.

The Volkswagen XL1 protoype

Hybrid system

With the hybrid system engaged the prototype XL1 accelerates from 0-62 mph (0-100 km/h) in 11.9 seconds and has an electronically limited top speed of 100 mph (160 km/h). The electric motor can deliver 100 Nm of torque from a standstill and works as a booster to support the TDI engine, which itself delivers 120 Nm of torque. Together, the TDI and E-motor deliver a maximum torque of 140 Nm in boosting mode.

The entire hybrid unit is housed above the vehicle’s driven rear axel, with the actual hybrid module with electric motor and clutch positioned between the TDI and the 7-speed DSG. Instead of the usual flywheel, the hybrid module is integrated in the DSG transmission case. The vehicle’s lithium-ion battery can also be recharged from a conventional household outlet.

In electric only mode the TDI is decoupled from the drivetrain by disengaging a clutch, and it is shut down. Meanwhile, the clutch on the gearbox side remains closed, so the DSG is fully engaged with the electric motor. Using what is known as “pulse starting”, VW says the restarting of the TDI while driving is very smooth. The electric motor’s rotor is sped up and quickly coupled to the engine clutch, which accelerates the TDI to the required speed and starts it.

Under certain conditions the load shared between the TDI engine and the electric motor can be shifted so that the turbodiesel is operating at its optimum efficiency level. Additionally, the gears of the automatically shifting 7-speed DSG are also always selected with the aim of minimizing energy usage with the engine controller taking into account parameters such as the accelerator pedal position and engine load, as well as the energy supply and mix of kinetic and electrical energy at any given time.

The Volkswagen XL1 protoype

Keeping it cool

The 0.8 liter two cylinder TDI used in the XL1 was derived from the 1.6 liter TDI found in the VW Golf and Passat. When required, the TDI is cooled through the activation of an externally driven electric water pump and an automatically controlled air intake system at the front of the vehicle designed to reduce cooling system drag. A second electric water pump, which is also used only as needed, circulates a separate lower temperature coolant loop to cool the starter generator and power electronics.

Design and aerodynamics

While the two seater XL1 borrows much of its looks from the preceding L1 model, it has been widened to allow for side by side seating rather than the tandem arrangement seen in both of the previous 1-Litre cars. The XL1 measures 12.75 ft (3.88m) long, 5.46 ft (1.66 m) wide and 3.79 ft (1.15 m) high, giving it a length and width similar to a VW Polo, but with a low profile comparable to a Lamborghini Gallardo Spyder. With a frontal area of 1.5 m2 and a drag coefficient of 0.186, the XL1 yields a total drag, or Cd.A value of 0.277 m2.

Viewed from above, the car is widest at the front and narrows towards the rear for an improved aerodynamic profile, which VW says resembles the aerodynamic lines of a dolphin. The dolphin-like looks continue to the side profile with the roofline tracing an arc from the A-pillars to the rear.

To prevent air turbulence the rear wheels are fully covered and the air flows have also been optimized by small spoilers in front of and behind the wheels, while the door mirrors have been replaced with digital cameras that send images to two displays inside the vehicle.

The Volkswagen XL1 protoype

Instead of the aircraft-style canopy door of the first 1-Litre and the L1, the XL1 sports wing doors that are hinged low on the A-pillars and just above the windscreen in the roof frame, so they swivel slightly forwards as well as upwards for easier access.

At the front end there’s no longer a typical radiator grille with the actual air intake with electronically controlled louvres for cooling the TDI engine, battery and interior located in the lower front end section. There are also energy-efficient dual LED headlights and narrow turn indicators.

LEDs are also prominent at the rear with a strip of red LEDs integrating reversing lights, rear lights, rear fog lights and brake lights, framing the top and sides. The coupé-shaped roofline has no rear windscreen but includes a large rear boot lid that covers the drive unit and 100-liter luggage space.

The Volkswagen XL1 protoype

When the L1 was unveiled in 2009, Volkswagen indicated it would be entering production in 2013. We’ll be interested to see if this updated model is on track for that date or whether the company hopes to bring the XL1 into production before then. All will hopefully be revealed this week when Volkswagen unveils the XL1 at the Qatar Motor Show, which runs from January 26 to 29.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
32 Comments

I like the front and the concept

Bill Bennett
25th January, 2011 @ 09:38 pm PST

I like it!

robinyatesuk2003
26th January, 2011 @ 04:54 am PST

Yes Please.

Not stellar performance numbers but very adequate.

Clearly they have matched the battery pack and electric motor to achieve the 1/100 ratio but they should also offer a larger battery and larger electric motor just like any other engine performance upgrade.

Muraculous
26th January, 2011 @ 06:16 am PST

This drivetrain in an Aptera would be very cool.

Bruce H. Anderson
26th January, 2011 @ 06:34 am PST

Wow! Now how low could they price it?

cmaglaughlin
26th January, 2011 @ 07:07 am PST

One of the best examples of weight-mass efficiency and aerodynamics I've seen - bested by the addition of clean-burning, high-efficiency TDI drive/generation. I'm stoked ! Bring it on VW, but please don't water it down for production (okay, maybe a rear window and interior mirror)...

JD Howell
26th January, 2011 @ 07:14 am PST

The aerodynamics are very good and so is the power system. The weight is low and the structure of the body should be a model for all future cars.

If the battery is used in combination with the diesel mainly for acceleration and not for extended periods of time, then perhaps a capacitor system might take the place of the lithium batteries.

I will be looking forward to seeing this vehicle reach the consumer market.

Adrian Akau
26th January, 2011 @ 07:56 am PST

I'm curious as to why they unveiled this new gas miser in a country that's major export is oil?

Tim Smalley
26th January, 2011 @ 08:00 am PST

Why do people refer to the rear window as a 'windscreen'?

Terotech
26th January, 2011 @ 08:00 am PST

The figures given are very impressive......for Quatar and other warm weather regions. My question is; can it survive Maine winters? I'm talking about after the roads are plowed from snow, then sand and rock salt mix is spread out on the roads for melting and traction purposes. This sand and salt will accumulate on the vehicle's underside and fenders. This will create not only corrosion problems but ice build-up in freezing temperatures that can hamper steering mechanisms. Also, what would be the average cost of this vehicle to consumers?

Facebook User
26th January, 2011 @ 08:26 am PST

The big question they have totally skiped over (unless I seriously missed something) is how much will this cost. Is this another Tesla Radster, suitable only for the super-rich? I assume so, because of the mention of "limited production".

The other question is the lack of a rear window. I assume this was for aerodynamics, but it soudns like a serious safety hazard. Maybe there is a rear-mounted camera?

Leithauser
26th January, 2011 @ 08:46 am PST

I like this. I think if I had a choice between this and the Aptera, then I would choose this.

Paul Anthony
26th January, 2011 @ 08:53 am PST

To all seeking to know the cost...

The title says "prototype" and prototype = Not for sale!

Give it some time, at least for VW to announce something.

steve.rioux
26th January, 2011 @ 10:02 am PST

set his sights on creating a practical everyday use production car with a fuel consumption of 1.0 liter per 100 km (235 mpg).

@ Leithauser: This is a practical everyday car... That would mean in my dictionary that it is affordable for the average person. Volkswagon means people car in German. Can't have a people car if it's too expensive...

Daniel Lafontaine
26th January, 2011 @ 11:01 am PST

I've been following this VW high mileage project since it started. This is truly amazing. Truly eye opening. But remember the sad fact about the end result of the mindset of this company. They will always go for the high end product.

They will never make a bare bones 2 passenger VW that will get high mileage and will cost under 7,000.

I really hope that Tata Motors will make a product utilizing these new insights so the world can have a benbifit from this technology.

froginapot
26th January, 2011 @ 11:20 am PST

Why don't they just make an inexpensive small enclosed car with a simple and light engine without the hybrid system (that adds to complexity, more failure prone, more weight, & larger size) with low drag coefficient that is easy to maintain? Look at the old Civic or the DIY Geo Metro with the boat tail, they get great millage. Look at some of the European small diesels.

Vadim
26th January, 2011 @ 11:27 am PST

Where can i buy one?

Facebook User
26th January, 2011 @ 01:38 pm PST

To make the car practical to consumers they'll have to make some compromises, hopefully not too many though. The price will have to be around 30k dollars and it will have to be able to carry four people and ten bags of groceries, at least. Otherwise it will just be a rich guy's toy.

Dean Mindock
26th January, 2011 @ 03:25 pm PST

Hmmm... reminds me of another market failure, the First Gen Honda Insight. Of course, I like it, but the 2-seater/futuristic styling did not find buyers.

..and I like this, too, so it's doomed! ;)

Matt Rings
26th January, 2011 @ 03:31 pm PST

Deisel @ 0.17$US/litre in Qatar.. I wonder what market they are hoping to capture?

KLM
26th January, 2011 @ 07:10 pm PST

Looks possible but will need environment cotrols as the windows don't open, great concept.

FL Phantom
26th January, 2011 @ 07:39 pm PST

we want to have it on the street as soon it's posible!

Facebook User
27th January, 2011 @ 03:28 pm PST

What would truely be impressive is if they could run this on bio-diesel. With such low consumption, it would make this a truely green car if it supported bio-diesel.

Australian
27th January, 2011 @ 05:29 pm PST

Congratulations to VW on creating this version. I too have been following the design with interest and I would like to see them work on the version where the passenger sits behind. If they are able to achieve MPG figures with a side by side seating position, I can only think that with the narrower frontal aspect of the passenger behind, the CoD would be further reduced and higher MPG achieved. There are a multitude of folks that travel alone and such a vehicle would be quite practical if it could be produced at a reasonable cost. People wondering about cost should take note of the interior of the XL-1, it does not speak of a high-cost vehicle. d;-)

Jetwax
27th January, 2011 @ 08:53 pm PST

Great progress - but still held back by a turbo diesel engine not operating at its optimum - and they state it in article - "so that the turbodiesel is operating at its optimum efficiency" - why not un couple it competely from the drivetrain and run a generator engine which runs continously at its optimum - I still prefer the "turbine hybrid" concept - If only we get away from this absurd obsession with speed - this concept would be awesome http://www.theengineer.co.uk/in-depth/analysis/jet-power-bladons-microjets-enable-jaguar-turbine-hybrid/1005528.article#Scene_1

The key downside with this is it requires the car manufacturer's to move away from all the R&D they have invested in engines and accept that you actually have to think completely fresh in terms of the main propulsion. Honestly I think this may come but not in the obvious short term

myale
28th January, 2011 @ 05:24 am PST

How do I get my name on the list to line up for this New VW? WOW! What great News. This will ..."Pay for Itself'...Just by the Savings !

WDR031927
28th January, 2011 @ 09:39 pm PST

When I worked for Bell Labs, the 200 kw gas turbine auxiliary power plant used in the Bell system consumed more fuel per hour idling (zero net output) than the 200 Kw Diese

auxiliary power plant did at full output.

There is a folklore that people who think about hybrid vehicles have that "running andn engine at "optimal speed" results in maximum efficiency.

If one looks at a real engine map, the best efficiency is at maximum or near maximum torque at almost any speed.

In addition, if you run an engine to runa gnerator to charge a battery and then run the battery to run the electric motors in the drive , there is a doubling of the inneffieciency of the two electromagnetic machines, as well as the input-output inefficiency of the battery charge discharge process.

rgorman
29th January, 2011 @ 01:23 pm PST

Hurry up. In fact I settle for 100mpg if it can be delivered quicker.

Mark A
29th January, 2011 @ 10:52 pm PST

The XL1 should take the place of the L1 for a number of reasons.

1. The Cd of the XL1 is lower than the L1

2. The XL1 combined turbodiesel-electric has higher power

3. The inside seating capacity of the XL1 is much greater.

4. The weight of the XL1 gives it stability under side wind conditions as compared to the L1.

5. The mpg of the XL1 is greater than the L1

6. The XL1 tapers in the back (dolphin design) while the L1 remains untapered which would account for the lower Cd of the XL1 even though the frontal area is greater

7. It would not make sense to have competitive sales between the XL1 and the L1 unless the price differential was in the order of about $30,000.

Adrian Akau
31st January, 2011 @ 03:08 pm PST

Lots of expensive component materials in this prototype so it remains to be seen if they can sell such a car for a reasonable price. Of course, reasonable to a person like myself on fixed low income may never come about so I am stuck with building my own vehicle borrowing from all the latest manufactures tricks for high mpg plus a few of my own! Maybe Tata Motors will come through with a minimal car for America and save me?

Will, the tink
6th February, 2011 @ 03:12 am PST

Dear Will the tink,

I also wish some of this technology would quickly filter down to the lower priced cars. There is a proposal that car manufacturers produce cars that can run at 60 mpg but the manufacturers have shown they are against this proposal. Perhaps it is because the plants for manufacturing the car bodies would have to be upgraded. I think the XL1 clearly shows that it is feasible to manufacture high mpg cars. While the price is not given and may be rather high, we at least know that the technology is available for this type of production. If VW is serious in manufacturing the XL1, we may see many new upgrades of vehicles from other manufacturers who wish to remain competitive.

Adrian Akau
6th February, 2011 @ 05:46 pm PST

How about a 1992 modified Honda Civic reportedly getting 95mpg at 65MPH with backyard modifications. http://www.gizmag.com/diy-honda-civic-as-aerodynamic-as-an-aptera-gets-95-mpg/10869/

Ok, so it is not beautiful, the point is that high mileage is possible without the expensive new plants, materials and engines. Again VW, shoot for 100mpg and no one will complain if the price is right. Come on, you knew that all along.

Mark A
6th February, 2011 @ 10:37 pm PST
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