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Audi A1 e-tron concept - Click above for high-res image gallery

After teasing us with a few goodies yesterday, Audi has just released technical details on its new A1 e-tron concept that debuts later today at the Geneva Motor Show. As we already knew, the A1 uses an extended range electric architecture like the Chevrolet Volt, but with a compact and power-dense Wankel rotary engine/generator to keep the battery alive after power from the grid is depleted. The diagrams released by Audi show that the Wankel is mounted in the car's rear behind the T-shaped battery pack that sits mostly under the rear seat.

The lithium ion battery pack has a capacity of 12 kilowatt-hours, which is claimed to provide about 30 miles of range on a charge. Unlike the 1,000+ pound pack in the original e-tron concept, this unit weighs in at just 330 pounds. The electric motor provides a standard output of 45 kW or 61 horsepower, though peak power of 75 kW or 102 hp is available in short bursts and keeps the car's 0-62 mile-per-hour time around 10 seconds. The motor and all of the power electronics reside in the car's front where the internal combustion powerplant of a conventional A1 would normally be found.

The Wankel weighs in at just 154 lbs and displaces just 254 cc of volume in its single rotor. The whole unit is small enough to sit below the cargo floor of the A1. Running at a constant 5,000 rpm, the rotary motor can extend the A1 e-tron's range to 130 miles. Why not longer? The fuel tank holds only 3.17 gallons. With the Wankel running, Audi says the A1 e-tron will return about 124 miles per gallon U.S.

Of historical note, the first ever production car with a Wankel rotary engine was introduced by NSU back in 1964. NSU later merged with Auto Union, which also included Audi, the sole surviving brand of the group.

[Source: Audi]
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Audi A1 e-tron – electric driving in the city

The new e-tron model series from Audi will gain another new member at the Geneva Motor Show: The Audi A1 e-tron is a Mega City Vehicle (MCV) with an innovative drive technology. It comes equipped with a powerful electric motor for zero-emission driving in the city. There is also an internal combustion engine on board that recharges the battery in exceptional circumstances. The A1 e-tron is very agile thanks to the 75 kW (102 hp) peak power of its electric motor.

The technology of the Audi A1 e-tron
The e-tron model family from Audi is just a few months old, but it already has a number of members, for each of which Audi has chosen a different drive technology. The first e-tron, which debuted at the 2009 IAA in Frankfurt/Main, is a near-series high-performance sports car with electric motors for all four wheels. The study shown at the Detroit Motor Show in 2010 is a lightweight, compact two-seater with two electric motors on the rear axle.

The A1 e-tron now presents another approach – a compact electric car in the premium class. The four-passenger, two-door MCV city car was designed specifically for use in the metropolitan areas of Europe and North America and in the rapidly growing megacities of Asia and South America. The Audi A1 e-tron always drives on electric power; its internal combustion engine is only used to recharge the battery in isolated cases.

The integration of the new technologies shows the holistic approach that Audi is pursuing with electric mobility. The objective is to use the energy with the lowest possible losses. The precise interaction of the components, their intelligent packaging, and the efficient management of the current flows are the product of the expertise that the company has developed in this area.

Audi has developed a proprietary thermal management system to keep the battery, the electric motor, and the power electronics within their respective ideal temperature windows.

Behind the three e-tron models is a broadly diverse and modular technology platform that continues to grow very rapidly as Audi drives development forward.

The electric motor: 75 kW (102 hp) peak power
The synchronous electric motor of the Audi A1 e-tron is mounted transversely at the front of the car. Its low mounting position has a positive effect on the vehicle's center of gravity. Continuous output is rated at 45 kW (61 hp), with peak power of 75 kW (102 hp) available in short bursts. 150 Nm (110.63 lb-ft) of torque is continuously available, and peak torque is 240 Nm (177.01 lb-ft).

The electric motor sends its power to the front wheels via a single-speed transmission. The elegant, retractable selector lever on the console of the center tunnel used to choose between "Drive," "Reverse," and "Neutral" was taken from the first Audi e-tron.

The power electronics are mounted in the engine compartment above the electric motor. The most important components are the pulse-controlled inverter, which serves as the controller between the electric motor and the battery; the DC converter, which connects the high-voltage network with the 14 volt electrical system; a breaker unit to protect the high-voltage components; and the charging module. The socket for the standard charging plug is located behind the rings in the single-frame grille of the Audi A1 e-tron. A fully depleted battery can be recharged in approximately three hours from the 380 volt grid. A display immediately adjacent to the plug-in connection shows the current charge status and the charging time remaining.

The concept of the innovative Mega City Vehicle requires the electrification of key auxiliaries. The refrigerant compressor of the climate control system, for example, is electrically powered by a high-voltage electric motor that supplies only the amount of power needed at the time.

This increases system efficiency substantially compared to conventional concepts. Thanks to a special circuit, the climate control loop also functions as a heat pump that regulates the temperature of the cabin and the battery.

The power steering of the Audi A1 e-tron is electro-mechanical and thus particularly energy-efficient. An electronic brake system makes it possible to tap into the recuperation potential of the electric motors. A hydraulic fixed-caliper brake is mounted on the front axle, with two novel electrically-actuated floating-caliper brakes mounted on the rear axle. These floating calipers are actuated not by any mechanical or hydraulic transfer elements, but rather by wire ("brake by wire"). In addition, this eliminates frictional losses due to residual slip when the brakes are not being applied. In addition, the servo unit received a new, demand-controlled electric vacuum pump.

The large electric motor powering the A1 e-tron can convert braking energy into electric current and feed it back into the electrical system. The high degree of recuperation benefits overall efficiency. The electric control actions are imperceptible to the driver, who notices only the familiar, precise, and perfectly controllable pedal feel.

The battery pack: a compact T arranged below the floor
The energy storage unit is arranged below the floor, where it is ideal for the center of gravity and weight distribution. The battery pack is shaped like a T, with the short "transverse beam" filling the rear section of the center tunnel and the "cross-beam" filling that area in front of the rear axle where the fuel tank is otherwise located. The 380 volt lithium-ion rechargeable battery has a nominal energy content of 12 kilowatt hours. It comprises 96 prismatic cells and weighs less than 150 kilograms (330.69 lb).

The Audi A1 e-tron can drive 50 kilometers (31.07 miles) emission-free in city traffic on the powerful battery. On longer trips, the battery is recharged by a particularly compact internal combustion engine mounted below the luggage compartment.

The range extender
The A1 e-tron concept car has a Wankel engine as a range extender, but other compact concepts are also possible. The small single-rotor Wankel has a chamber volume of 254 cc and runs at a constant 5,000 rpm in its peak efficiency window. The electronics also consider navigation data such as the destination and route profile to automatically activate the range extender as needed. The driver can also turn the range extender on and off as necessary with the push of a button The fuel tank holds 12 liters (3.17 US gallons).

The great strengths of the Wankel engine are the nearly vibration-free and quiet operation, the small dimensions, and the extremely low weight. Together with the generator, which is powered by the Wankel engine and produces 15 kW of electric power, the complete assembly weighs only around 70 kilograms (154.32 lb). This weight also includes the special power electronics, the intake, exhaust, and cooling unit, plus the insulation and the subframe.

Driving experience
The first defining impression that the driver of the Audi A1 e-tron gets is that of nearly total silence. Even the Wankel engine in the back can barely be heard when it is running.

The second characteristic perception is the power of the electric motor, nearly all of which is available instantly and thrusts the Audi A1 e-tron forward with authority. The innovative Mega City Vehicle, which despite its complex drive technology weighs only 1,190 kilograms (2,623.50 lb) delivers zero-emission driving fun in a modern and sophisticated manner. The vehicle accelerates from 0 to 100 km/h (62.14 mph) in 10.2 seconds and has a top speed of more than 130 km/h (80.78 mph).

The Audi A1 e-tron can also cover longer distances if the range extender charges the battery. The extra range, which is intended primarily for interurban driving, is 200 kilometers (124.27 miles).

According to the draft standard, the two different operating modes yield a fuel consumption of only 1.9 l/100 km (123.80 US mpg), which corresponds to CO2 emissions of 45 g/km (72.42 g/mile). In electric mode, there are zero local CO2 emissions - the compact A1 e-tron is thus ecological and economical.

The third impression that the A1 e-tron makes is that of a larger car. The compact two-door boasts all of the strengths of the new A1 model series – the carefully tuned, sporty chassis with specially designed 18 inch alloy wheels and 215/35 R18 tires; the generous, "grown-up" interior; the excellent fit and finish; and a multitude of high-end equipment.

The dark shade "ebony" dominates the interior. The seats – with stone gray seams – and the headliner are in "Alabaster White".

The concept car in Geneva has a special "Aqua Mint, pearl effect" paint finish; the contrasting roof arch is offset in "High Gloss Steel dark." As with the other two e-tron models, the 18-inch wheels with a 20-spoke turbine design convey the high-tech aspiration of the concept.

The rear diffuser with aluminum trim lacks tailpipes. This emphasizes the width of the vehicle and suggests the low emissions. The two front fenders are emblazoned with the "e-tron" logo.

The "Aqua Mint, pearl effect" exterior color carries over into the interior, where it adorns the door panels and the center console. The shift lever is a special leather-wrapped design; as is typical for the e-tron models, the start-stop button was placed in the front of the center console. A specially designed battery cover at the front of the car and the range extender engine with its cooling fins displayed under a sheet of glass in the luggage compartment also serve to visually underscore the clean technology of the A1 e-tron. And because an innovative drive concept also calls for innovative information management, the concept car features a freely programmable instrument cluster with a virtual display surface and innovative display and operating concept.

The equipment and data specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.

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    • 1 Second Ago
      • 5 Years Ago
      Thanks for that historical note Autoblog! I was seriously wondering where Audi got a Wankel rotary from.
      • 5 Years Ago
      correct me if i'm wrong but i believe this says that the audi will receive 124 mpgs and that times three is roughly 372 mpgs. that is extremely efficient as well as convenient
        • 5 Years Ago
        124 mpg (if using the EPA EREV/PHEV method of fuel economy) reflects a combined fuel and electricity consumption. EPA has adopted a method for combining electricity and fuel for vehicles like this. Multiplying 124x3 is incorrect, since the 124mpg figure reflects the combined fuel and electrical energy used. And dividing by 3 is incorrect since the method to combine fuel and electrcity depends on the performance over standard dynamometer drive cycles.
        • 5 Years Ago
        How is this a surprise. This is a scam like the Volts 230MPG.

        • 5 Years Ago
        My thoughts exactly. Not sure where some people here are coming up with 41 mpg, etc. Remember people the standard-fare A1 is getting 55mpg. The hybrid is NOT going to get worse mileage than the base car.
      • 5 Years Ago
      "Well doubt Audi would go through all the trouble to engineer a Wankel, electric hybrid when their standard fare A1 gets 55 mpg already.Yes, this car gets 124 mpg and not the 41mpg as your calculation suggests."


      Yeah lets forget math as a way to figure things out and use wishful thinking instead.
      The Wankel is not used for efficiency, it is used for light weight and small size. ~40 MPG is about all you can expect from a car that uses a Wankel, even a very small one like is used here.

      So even before we get to calculating anything you can be fairly certain of getting 40mpg +/-10mpg. But then Audi was kind enough to provide the numbers so we can actually calculate the MPG at 41mpg.

      It all makes sense. Range extended MPG is not really the point of ER-EVs, they are really meant to be used as EVs with gas engine for emergencies. Especially this one, with it's paltry 20HP generator.

      • 5 Years Ago
      What I don't understand is the choice of a wankel engine. They are not strong when it comes to emissions performance or fuel economy.
      I understand there is a size/mass benefit vs. power output, but they're not clean nor efficient in "classical" form.

      Maybe Audi has new tech they're using with the rotary that will see this engine return to production in larger numbers. They really are wonderful little things.
      • 5 Years Ago
      You can hold more fuel in a gas can than in this gas tank.
      • 5 Years Ago
      you are all asking the same question about the mpg. This is an ER EV, meaning a plugin hybrid. They use a formula to guess how often they use gazoline as opposed to electric and another one to give an equivalent kwh elecgas.
      The point is that this is a urban vehicle that most of the trips will be bellow the 30miles range and will be electric only and thanks to the generator it can still be used outside the city it is just not ideal for really long trips.
      • 5 Years Ago
      i'm surprised they use a Wankel, i thought those things were thirsty, or maybe Mazda is just doing it wrong.
        • 5 Years Ago


        So what was all that you were saying about wankels not being efficient diesels? Yeah, it was pretty apparent you were talking out your butt. And continue to do so. How about you come back to this discussion when you have a working knowledge of the design involved, hm?
        • 5 Years Ago
        Wankels are thirsty when they operate outside a very narrow band. When operated at their efficiency maximum they are not much worse than a normal gas engine. In the case of range extenders the small packaging is an advantage of the Wankel, so it makes much sense in this application.

        The Wankel engine is still popular around aircraft suppliers as APU engine. Since it is possible to build Wankel diesels (both pressure ignited or ignited by spark) that run on Jet A1 those Wankels are often preferred to turbines since they are more efficient in the 10-30kW range.
        • 5 Years Ago

        You can't play the skeptic if you don't bring anything to the contrary to the table. "I don't think so" doesn't fly unless you've got some sort of working understanding of these motors which, from the sounds of your recent posts, is negligible. Spend some time on the SAE website first, read some papers on Wankels or don't comment. An uninformed opinion is a useless opinion.


        BTW it's not spark ignited. The PATS engine only has a glow plug for cold operation.
        • 5 Years Ago
        Nice Try Nate.

        But you haven't exactly offered anything substantive. One obscure German comment about a manufacturers claiming aircraft APU being better than their aircraft APU. Nothing backing it up. But in the end it hardly matters. We are talking about petrol burning car engine here, not a kerosene burning aircraft APU.

        Here are some numbers: Quarter mile times and MPG from consumer reports:

        RX8/MX5/S2000/Corvette Z06

        15.2 15.4 14.4 12.3

        14 / 22 20 / 35 19 / 30 13 / 28

        Not only does the RX8 have brutal fuel economy compared to other sports cars, it also has abysmal highway mpg showing that even in steady state load it is has terrible economy.

        These numbers are from actual testing of a road going Wankel, vs the unsupported comment you found about comparisons to turbines.

        Wankels are quite inefficient compared to piston engines. Even compared to a fire breathing tire shredding Z06.
        • 5 Years Ago
        "So what was all that you were saying about wankels not being efficient "

        That is hardly definitive and only indicates they are more efficient than a small turbine (which aren't very efficient either).

        • 5 Years Ago

        That's great and all but you're still talking about cars with totally different gearings, driveline losses, etc. To compare engine to engine you need to know both the theory behind them and the practical issues with them. And that's the problem. You clearly know crap all about the things.

        You're judging all wankels based on what is frankly Mazda's painfully primitive last iteration. There are 3 issues with the wankel and I'll break them down for you:

        1) Wankels use cast iron to keep the rotor faces hot to increase combustion temps (wankels use low temp combustion so NOx numbers are small but HC numbers are larger). For reference, it's just sheer brilliance of design that allows this to happen. The only piston engines that used cast iron pistons were steam engines of the 1800s and they ran at barely any RPM. Mazda does this because while using aluminum rotors would allow the engine to rev to insane levels (we're talking well into the 5 digit RPMs), the emissions would get worse because of the lower combustion temperature. However if you coat an iron or other heat-retaining surface on top of an aluminum rotor then you would solve the issues of proper heating of the combustion chamber. It turns out Ford has only just revealed it's now able to do cheaply and will start using it on its engines which is the first time a manufacturer has done this outside of rather pricey aerospace applications. So problem one is now a matter of cost rather than a matter of if it can be done.

        2)The wankel combustion chamber is not the ideal shape for the flame front to expand and so fuel ignites relatively slowly and some doesn't burn at all (it just sticks to the rotor face and gets flung out the exhaust pipe). This is why rotaries have 2 spark plugs per rotor. Racing rotaries actually had 3 which hugely helped the problem both of fuel consumption and subsequently emissions. Mazda for whatever reason (likely cooling and costs) has forgone this route but we might see it come to production in a future iteration. Regardless, add DI and suddenly the low speed issues of a cold combustion chamber, high fuel consumption at idle and sticking gas droplets all are hugely reduced. Again power goes up and torque goes up as well along the power curve.

        3) The surface area to volume ratio of the combustion chamber is high. This is a very easy one to fix, you simply add eccentricity. The rotors spin off-centre more to create a more voluminous space for the explosion to happen in. Torque goes up a ton because thermal efficiency shoots up and everything else benefits too. Also, you are essentially carving a bigger hole through the air with the higher eccentricity which translates into a bigger engine. However within it is significantly more space so the engine becomes lighter.

        We know Mazda has developed the 16X by addressing both points 2 and 3. 1 could well be in the pipe now since Mazda could still be buddy buddy with Ford enough to license the tech. Still with just changes in eccentricity, volume changes and DI combined with more aluminum, Mazda has made the 16X lighter than the last 13B as well as 30% more fuel efficient and torquey.
        • 5 Years Ago
        Hint: Google for PATS Wankel APU
      • 5 Years Ago
      How does this 'advance [the] ER-EV concept'..? 130 mile range for a gas / electric hybrid sounds like a big step back to me. There are pure EVs that have that kind of range. What's the point in adding a gasoline engine if it's not going to add any range. Does Audi even know what the 'ER' part of ER-EV is supposed to stand for.
      • 5 Years Ago
      ... it seems to me to get the 124 mpg claim.. you'd have to use the metric... they are storing 3.17 litres of fuel.. or about a US gallon.... so their claim will not be far off....
        • 5 Years Ago
        I was wondering about those numbers too.
        On the face of it, as reported, a 3 gallon tank and 124mpg on ICE operation does not work out to a range extension of 100 miles.
        Something is screwy in Denmark....

        Would be great if the error is that the range is extended by 372 miles or so.... hahahahahaha..... yeah... that and santa clause.
      • 5 Years Ago
      Did they seriously not have enough space to give it a bigger fuel tank?

      With only 130miles each fill up, that sounds like it will require many visits to the gas station. I realize that each trip will only cost you $10 or so, but it seems annoying to have to waste time there like that.
        • 5 Years Ago

        Previous story. The Genset is 15KW =~20HP.

        Which is ridiculous. That is so tight that if you were driving down a highway in the dark with high beams and the stereo on, you would probably have to drive slower.

        • 5 Years Ago
        Ever heard of gasoline going bad? This is actually a pretty good idea. Like the use of the Wankel
        • 5 Years Ago
        Huh? It gets 124 MPG, so it only needs a bit over 3 Gallons to have more range than the car you're likely driving today.

        Excellent advances for someone that wants one of these green cars. Sounds like a good second city car, but for me, my heart is in the RS5 !!!
        • 5 Years Ago
        @snowdog so you've identified the only perspective market for this car as, essentially, europeans, and audi, a European car company has introduced the concept at a European autoshow and you can't see it being built coming from a north American perspective. Lmao. Good times
        • 5 Years Ago
        @ zamafir

        That comment was full of win. I wish there were more like it on this blog.
        • 5 Years Ago
        Fuel Tanks is small because this car is a short range city car and fuel tank is only for emergency use.

        Once you are running on range extender you only have 20 HP. You are not going to want to drive any distance like this. This is limp home type operation.

        Basically this is a very limited car for people who barely need a car.

        I can't see this being built.
        • 5 Years Ago
        Ahhh!! I called this one waaaaay back when. One by One they are coming around to GM's way of thinking. First Lotus, now Audi. The VOLT is the game changer GM and I said it would be. 230 mpg may not be so far fetched after all.

        November is just so damn far off, these cars should be on the road NOW. However, don't want to see it become a Toyota. So GM, beat on it now, fewer recalls later.

        • 5 Years Ago
        Actually I didn't know about that, but that's less than a normal car, so I stick to my point.

        I feel like I full up my car too often as it is, and it lasts around 250 miles each tank.
        • 5 Years Ago
        @ minesasecret , maybe this is meant to be an urban car , not a cruised. even if it was a cruiser , mostly women will buy this and we all know how how often they need to stop at long trips anyway :)
        • 5 Years Ago

        Wait except as far as I know you can't just convert it like that since that 20hp is used to generate electricity. If it really is 20hp but that is beyond the point.
        • 5 Years Ago
        @ Dr. Greenthumb , GM's way of thinking ? GM didn't invent the serial hybrid.
        • 5 Years Ago

        Where did the 20hp number come from? I don't see that.
        Also, I don't think they would add an entire ICE system to extend the range from 30miles to 150 miles but with the last 120 miles (on ICE operation) being only in a 'limp-home' mode.
        That doesn't make a lot of sense.
      • 5 Years Ago
      The article seems to give enough information - the car will do 30 miles electric, and an additional 100 miles on 3.17 gallons of gasoline. How do they end up with a claim of 124mpg? Well, I'd imagine in much the same way Chevy Volt claims 230mpg. By changing the distance traveled, you can fudge that final mpg number any way you like because the first 30 miles is infinite mpg.

      So, all they have to do is make their test trip 40.2 miles. That trip will use 0.32334 gallons of gas, resulting in 124mpg. Just like the Volt's 230mpg claim, it is completely meaningless.
      • 5 Years Ago
      EWWW! The different color pillars make it look like a mini cooper!!
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