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Audi R18 e-tron quattro hybrid with flywheel energy system wins Le Mans; first hybrid win there

The R18 e-tron quattro hybrids at work. Click to enlarge.

Marking the first victory of a hybrid vehicle at Le Mans, the Audi R18 e-tron quattro (earlier post), equipped with Williams Hybrid Power’s (WHP) electromechanical hybrid flywheel system, took the top two spots at the 80th running of the endurance race over the weeken. The win was Audi’s 11th Le Mans victory. The four Audi R18 cars (two hybrid, two diesel) from Audi Sport Team Joest occupied positions one, two, three and five.

Operating at the rear of all four Audi R18 cars was the latest evolution of the compact V6 TDI engine with VTG mono turbocharger that was used at Le Mans for the first time in 2011. The new ultra-light transmission with a carbon fiber housing held up to the Le Mans endurance test covering a distance of 5,151 kilometers in all four vehicles with no problems, the company said.

The engine is a 3.7-liter turbocharged (boost pressure limited to 2.8 bar absolute) 120° V6, 4 valves per cylinder, DOHC diesel direct injection TDI using a fully stressed aluminum cylinder block and equipped with a diesel particle filter. The engine delivers power of more than 375 kW (510 hp) and torque of more than 850 N·m (627 lb-ft).

WHP designed an entirely new, ultra-lightweight electric flywheel and associated power electronics for the Audi R18 e-tron quattro, working closely with Audi engineers to fully integrate the system into the car. The system provides 150 kW of power and has a top rotor speed of 45,000 rpm. The key features and benefits of the WHP system are highly suited to endurance racing and this made the WHP flywheel the prime candidate for Audi’s project when compared to other technologies such as batteries, ultra-capacitors or mechanical flywheels, WHP said.

One vehicle axle (rear) of the R18 e-tron is powered conventionally, the second (front) by two water-cooled 75 kW motors with integrated power electronics. The system integrated into the front axle includes two drive shafts, the Motor Generator Unit (MGU) supplied by Bosch, planetary gearset, the WHP KERS system, an insulation monitoring unit for high voltage safety, and the control system.

On the Audi R18 e-tron quattro, kinetic energy is recovered on the front axle during the braking phase. In the process, the wheels drive the MGU. The braking zones permitted are defined by the controller. Power from the Motor Generator Unit accelerates the carbon-fiber flywheel, which runs in a high vacuum.

After the corner is taken and the driver accelerates again, the system delivers the energy to the front axle. The regulations allow 500 kJ of energy to be transferred to the front wheels between two braking phases. The planetary gears adapt the transmission ratio during acceleration and braking. The two independently powered axles on the e-tron quattro are synchronized exclusively via electronic control strategies.

This control occurs automatically without driver intervention. The entire charging process (recuperation) is controlled by two parameters: the deceleration of the car—i.e., the braking process—and subject to the accumulator’s state of charge. The energy emission process (boost) is defined by the minimum speed of 120 km/h stipulated by the regulations, the race strategy selected, the throttle pedal movement and acceleration of the car.

With the e-tron quattro in combination with ultra lightweight design, we put a completely new technology on the grid and immediately won with it—this cannot be taken for granted by any means, particularly here at Le Mans. This weekend again showed the type of things that can happen in this race and how important perfect preparation is.

—Rupert Stadler, Chairman of the Board of Management of AUDI AG

The 2012 running of Le Mans also had two hybrid entries—the TS030 HYBRID (earlier post)—from Toyota, featuring a super capacitor-based hybrid powertrain.

Accidents took both Toyota hybrid vehicles out the race this year.

Porsche is also using a WHP flywheel energy recovery system (KERS) in its 911 GT3 R Hybrid. The GT3 features an electrical front axle drive with two electric motors developing 60 kW each supplementing the 480-bhp (358 kW) four-liter flat-six at the rear of the 911 GT3 R Hybrid. (Earlier post.)



This race mean nothing on the green level because there is just one or two car that use the same technology and that have been made with dubious rules with different engine size, different fuels, different superchargers or turbos. We don't find similar technologies on regular car on the market. A bev on this track cannot even make a single lap at the same speed. This is a victory of fossil fuel over any alternate technology and we can see ads from shell all over the track and this pollute the air , soil and surrounding water around the track and where the fossil fuel have been extracted and transported and refine. Usually traffic in that area is low in the night but for this event pollution is done 24/24 impeding children to sleep at night. If we take account of the engine oil use it gets even worst. the hybrid system is just a fake because they can use bigger engines for doing so or the size of the engine is limited to a given size by arbitrary rules that change every years. This is mainly a publicity event made by oil aficionados, we can see and hear everywhere for 24 hours. If we remove the fossil fuel from that event then only cyclists could have done the show but for a couple of hours instead of an entire day. Most spectators run to the event with fossil fuel cars, saw many fossil fuel ads and racecars and none of the big brands don't offer any hybrid sport cars for sale so this has given nothing for the green scene, quite the opposite in real life. I recommend to postpone any audi or toyota car expenditure till they start to conceive, build and market green sport car that don't use a drop of gasoline, cost less and go faster then these fossil fuel cars.


I suppose what matters is does any of this technology trickle down to cars we can buy in reasonable numbers.
Diesel costs extra, and hybridisation costs extra.
Will anyone be prepared to pony up for a diesel hybrid ?
Hard to tell - no big sellers yet, though we have a lot of Hybrids (in Japan) and diesels (in Europe).
Will anyone be prepared to pay a double premium to drive a diesel hybrid if it gets (say) 70 mpg(US) [Assuming a Prius gets 50 mpg] ?
My guess is you will sell a few luxury (Audi A8's and BMW 7series's, but the A4 and 3 series would be too expensive.


Yup, it has two aspects, both with some value.

As a techno-sport it is entertaining.

And I think we can assume SOME of this technology will trickle down or at least contribute somewhat to cars we can buy in reasonable numbers.

Could be worse. . .


The changes they've announced today for 2014, including getting rid of restrictions on engine size, type, etc and simply limiting the amount of energy spent per lap truly does go towards the way technology can serve cars today.

Those types of rules are much more likely to produce tech that trickles down to every day automobiles for fuel efficiency.


A Ford GT40 Mk. IV covered 5232.9 km in 1967.

Could be embarrassing to travel 80 some km fewer after 45 years.


Please take a look at a 1967 circuit map and compare it to 2012. They've added several turns including 2 chicanes on the Mulsanne straight since then.


Nickolaos, good link. I guess it's like EPA ratings - always some change to fudge comparisons. The curves extra curves break the straight-away, though an extra quarter mile in eight miles isn't much.

In the 1980's, there were $million dollar bids for 0.1 GB mainframe computer memory. Last week I bought 8 GB of tablet computer memory for $5.

That's an improvement of ~1,600,000,000 times.

That's high performance.


1. These turns were introduced for safety reasons. Nobody cares about EPA-ratings in motorsport.
2. It's not about the extra distance. It's about the fact that the new racecars need to decelerate and accelerate twice just in this long straight.

Besides, hybrid does actually make more sense in motorsport than in normal driving, because 40% of the energy is used for braking. Recycling braking energy reduces the amount of fuel/weight needed to carry around and/or reduces the number of time consuming stints needed.
For comparison: Non-race car drivers sometimes drive 2 hours without even touching the brake once.



You have to consider that they used to do 240mph down the Mulsanne Straight. Now they top out at ~208mph and they have to brake twice and accelerate again during that same "straight" because of the chicanes. There are so many more curves now, that they don't completely optimize the car for top speeds but more favor downforce for cornering.

They intentionally added those chicanes to slow the top speeds for safety reasons. When you consider how much extra time they now spend on that one part of the track and how much slower they have to go through that section over ~390 laps....that is a LOT of wasted time compared to the 1967 course.

I'm surprised they actually get the distances they do these days. :-)

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