The Citroen 2CV: cleantech from the 1940s

If you sometimes wonder why more energy efficient technology does not bring about more energy efficient cars, you should take a look at this collection of Citroën brochures (most of them in foreign languages) from the fifties, the sixties, the seventies and the eighties (more here, here, here and  here).

These are all original, scanned leaflets of the legendary French hippie car "2CV" or "Deux Chevaux" (known as the "duck" or the "goat" in several European countries). In spite of all the high-tech that has been squeezed into cars since then, the 2CV from 1949 is still more energy efficient than the smallest model of the French car designer today. Why?

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"If we really want more energy efficient cars, the 2CV shows us that we need not more, but less technology"

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The 2CV was produced from 1949 until 1990 and sold almost exclusively in Europe. At the time of its introduction the car had an engine capacity of 375cc, a maximum power output of 8 horsepower (DIN-HP) and a top speed of 65 kilometres an hour (40 mph).

In 1954 the power was tuned up to 10 HP, which brought the top speed at 80 kilometres an hour (50 mph). In 1974 the power output rose to 24 HP, with a top speed of 102 kilometres an hour (63 mph). Later models had an engine capacity of 602cc, a maximum power output of 30 HP and a top speed of 120 kilometres an hour (75 mph).

500 kilograms

In spite of the much higher performance (an almost doubling of engine capacity, 4 times as much power output and a top speed almost twice as high) the weight of the hippie car remained the same at about 500 kilograms (sources: 1,2,3)

Today, there is not one car which comes even close to these figures. The smallest model of Citroën now on the market, the C1, weighs 810 kilograms (despite the use of lighter materials). The Citroën C1 has an engine capacity of 998cc and a maximum power output of 68 HP, and it does 157 kilometres an hour (98 mph).

8 x more power

Compared to the first 2CV models, the weight of the smallest Citroën today has almost doubled, while the top speed more than doubled and the maximum power output rose by a factor of eight.

Surprisingly, the fuel consumption remained more or less the same. The C1 consumes 4.6 litres per 100 kilometres (61 miles per gallon), the 2CV consumed on average 4.4 litres (64 miles per gallon).

It is obvious that the engine of the C1 is many times more energy efficient than the engine of the 2CV, since the latter needed the same amount of fuel to power a much lighter and much slower vehicle.

In other words: if we would apply this modern technology in a car that is as light and slow as a 2CV from the fifties, we would now drive cars that scarcely burn any gasoline. Unfortunately, all technological progress was devoured by more weight, more power, more speed, more comfort and more electronics.

Safety belts

Part of the extra weight is the consequence of safety measures. Car manufacturers always hammer at this and of course more safety is a good thing. But, because at the same time the speed of the vehicles has raised substantially, and higher speeds mean more serious accidents, part of this progress is negated - just like the higher energy efficiency is negated by the higher performance. Moreover, safety belts are still the most important reason why traffic deaths plummeted since the seventies, and the weight of that mechanism is limited.

Comfort

Another reason for the higher weight and energy consumption is the advancement of comfort and electronics. The first 2CVs hardly had a dashboard that was worthy of the name. The vehicles had no heating or air-conditioning - there was not even a fuel gauge.

If you wanted to know how much gasoline you had left, you had to stop and poke a dipstick into the fuel tank. Until the sixties, the windscreen wipers were driven by the wheels - and therefore did not work when the car was not moving (unless you powered them by hand).

The windows of the 2CV could not even be opened mechanically, let alone by electricity: they were pushed open with your elbow. In today's cars all these applications (and dozens of new applications) are run by their own electric motor.

These electronics push up energy consumption because they raise the weight of the car and because they consume energy themselves (electricity which is delivered by the combustion engine). If we really want more energy efficient cars, the 2CV shows us that we need not more, but less technology.

© Kris De Decker (edited by Vincent Grosjean)

Brochures found via Things Magazine & Tecnología Obsoleta

Comments (19)

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Links :

These sites have more information on the Citroën 2CV (in English).

Also check out the brochures of the Panhard, the Hoffmann 2CV, the Dyane, the AMI, the plastic Mehari and other Citroën models.

2CV paper models.

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More cars :

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• Overview of early electric cars (1895-1925): pictures and specifications
• Why the electric car has no (wireless) future
• Who killed the electric grid? Fast-charging cars need power peaks of 150,000 watts
• The age of speed : how to reduce global fuel consumption by 75 percent
• Automobiles on steroids : what if weight and horsepower had stayed relatively constant since 1980?
• Cars - out of the way

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Comments

[Marios]

(19)

I have read so many interesting opinions. The 2cv is a great car. I have been driving one for 16 years and I think it was ahead of its time. It has a great suspension, it's fun to drive and I love the way it looks, not to mention its practicality and the opening top. However, I think that a bit more technology would make it more fuel efficient, a bit more powerful (not to show off, but to overtake with safety) and I would like a quicker steering wheel. In any case, I really love this car and I think that in many ways it could show the way forward.

[Furlongs per pint]

(18)

Further to comment #3: the fuel efficiency conversions in the article are based upon the gallons being Imperial. For US gallons, the conversions become 4.6 l/100 km = 51.1 mi/gal and 4.4 l/100 km = 53.4 mi/gal.

Easy formulas for the conversions between l/100 km and mi/gal are:

to/from Imperial: 282.48 ÷ x = y

to/from US: 235.21 ÷ x = y

If x is l/100 km, then y becomes mi/gal; if x is mi/gal, then y becomes l/100 km.

[2cvman]

(17)

one thing you all forget..Aerodynamics! The 2CV has a dragcoefficient of 0.6. Twice as high as the more modern car.

[Colin Hawes]

(16)

I think your fuel consumption figures for the 2CV are a little optimistic. I drove two 2CV6s over 14 years.I never achieved 60 mpg.
On urban driving, I managed low to mid forties. If I "thrashed" them at maximum speed on the motorway it could be a poor as high thirties. If I took it easy on the motorway it would be mid to high forties. The best I ever achieved was 58 mpg. That was in 1991 between Kinlochbervie and Kingussie in Scotland. Mainly on fairly empty roads where I was taking my time and admiring the scenery.
It would be good to see a modern equivalent of the 2CV. But don't imagine the 2CV was ever low tech. Despite it's funny shape, it was pretty advanced for it's day.

[MBM]

(15)

One factor not mentioned here is the incredibly low emissions levels of modern engines compared to 40s powerplants. Although fuel usage is minimized by computer controlled engine management systems my guess is that efficiency would be higher yet if engines were designed purely for fuel economy.

[kdd]

(14)

I agree. It is not my wish to turn back the technological clock, but I think that many obsolete technologies can be an inspiration when designing new technology. The best of both worlds, as you describe it.

One thing to keep in mind though, is the embedded energy of many new, high-tech materials. Aluminum and Titanium, for instance, require much more energy to produce than steel. They are also lighter than steel, which can lead to a better fuel economy, so I am not saying they are by definition a bad choice. But it should be taken into account when you want to find out which car is the least damaging to the environment.

[Lupodriver]

(13)

It *is* possible to have the best of both worlds - modern safety and low fuel consumption of a lighter car.

I drive a VW Lupo 1.2 TDI 3L which is rated 4/5 stars by EuroNCAP for collision safety.

Although it rarely (ie. never) reaches the 3 l/100km (from which the "3L" comes) it NEVER uses more than 3.7 l/100km (61.9 MPG) - and that's not a theoretical number, but the one from the onboard computer.

The car seats four adults (the two front ones comfortably) and has sufficient headroom for tall people - although it doesn't exactly have a lot of boot space.

Sometimes the solution isn't winding back the technological clock, but using current technologies (turbo, electronic engine control etc.) with lighter materials (aluminium, titanium) - and keeping cars small when at all possible.

[Alex]

(12)

Grumpy makes a comment on impact protection, but the two pages he posts aren't comparing like with like.

The 2CV was crash tested in the 60's and 70's by being fired into a solid wall at 40-45 kph, the Citroen C1 is fired into a deformable barrier such than only the the front quarter of the car strikes at 64 kph.

So sadly it's nigh on impossible to compare.

As the former owner of a 2Cv who walked away from crashing one into the side of a Rover Metro at 50 mph, I can say they're surprisingly good. The bonnet's long, there's plenty of room between the engine and the driver's feet and of course there's no dashboard to crush your knees.

But less weight is the way to go, and roll on Gordon Murray's new vehicle as he's of the same mind and of course is a hugely capable car designer (think Maclaren F1).

[Ron]

(11)

2cv from 1970 onwards run on unleaded fuel, it can run on e85, this will cost you 25 euro for the conversion. The only problem is that the air cooled engine has a 9% co2 level.

[eddy]

(10)

No, no, no... this is all wrong. If we are to go down this route, let us not do it by halves: a bicycle is orders of magnitude more efficient and less polluting than a 2CV - probably more comfortable, and certainly better for health! Additionally, its top speed on a flat with no wind approaches 35mph - faster still (and even more *efficient*) if it is ridden skilfully in a peloton or a paceline!

The only possible advantage of driving a 2CV is if you are old and infirm or you need to a carry a pig. Most things that are carried in an average 2CV journey can be carried on a bicycle (either in panniers or a trailer) with no problem. To my mind, a car is for luxurious travel, shifting extremely bulky/heavy loads, or travelling very fast - since the 2CV cannot do any of these, prefer the bicycle (albeit, the hi-tech carbon-fibre bicycle!)

[Gene (Yvon Le Breton)]

(9)

Sorry but the leaded Petrol comment is not correct.
All aluminium head Citroens including the 2CV had and have steel valve seats. Lead in Petrol did many things, polution, upped octane, and cushioning to prevent (valve recession)but only in cast iron heads where the seats were ground in directly. While the octane of the fuel has to be in line with the compression ratio (3 different one in the 602 engines) leaded Petro and lead additivies are not necessary.

[Michael]

(8)

On the subject of efficiency and low emissions,I recently came across an interesting concept for a sort of modern steam engine,the Cyclone engine.Like other steam engines,torque is maximum at 0 RPM,therefore no transmission is needed,it doesn't need oil changes,it runs on any liquid fuel,and it's overall efficiency is in the diesel range.The emissions are kept ultra low because it is an external combustion engine,tuned for complete combustion.Other versions of the engine can run on waste industrial heat,solar,etc.
See: http://tinyurl.com/8tkmtk

[MBM]

(7)

One important additional factor is the regulatory insistence that automotive engines produce extremely low emission levels which unfortunately requires considerable use of high-tech materials and extensive computer controls. An eight liter Bentley probably produces less pollution in virtually every respect than the primitive powerplant of the 2CV. High tech will be unavoidable in future engine designs but the main ideas of lightness and simplicity are certainly attractive. Whether the public will be willing to buy vehicles that may be less "safe" but offer big improvements in efficiency is another matter.

[Adrian K]

(6)

Just as a by the by, the 2CV engine needs leaded Petrol,new cars don't. It's also air cooled, no water cooling. Just my penny's worth.

[Kris De Decker]

(5)

Sorry to send you away, but there is someone making an interesting comment on this somewhere else:

"To the gentleman who posits 'Impact safety means weight': incorrect. Impact safety is the result of good design. Good design adds no weight to the vehicle. Formula 1 race cars weigh as little as 440KG, and drivers often walk away from crashes at triple-digit speeds."

Read the full comment (physics included) here:
http://www.stumbleupon.com/url/www.lowtechmagazine.com/2008/06/citroen-2cv.html

[S.P. Gass]

(4)

Grumpy, that's a good point. I think the question becomes, would people be willing to give up crash protection for better gas mileage?

After all, the most important safety feature is the driver.

[S.P. Gass]

(3)

Excellent article. I doublechecked your mpg conversions because they sounded high... some online calculators are using 1 litre=.22 gallon whereas other sites show 1 litre=.26 gallon. I believe .22 is correct for liquids. That would bring the mpgs referenced down to 51 and 53 mpg respectively.

Regardless, you make a great point. I own a (slow) 1964 Ford Falcon which gets about 30 mpg, which is approximately the same as most new American cars get.

50+ mpg from 1940s technology is amazing, especially now that people are getting excited about Toyota Prius and Smart car which only get in the 40-50 mpg range.

[Grumpy]

(2)

One major reason why modern cars are heavier has been overlooked: crash protection.

Hit a non-deformable object at 30mph in a 2CV, and you will be seriously injured.
http://crash.citroenz.biz/2CV/

Hit one at the same speed in a C1, and you will walk away relatively unharmed.
http://crash.citroenz.biz/C1/

Cars with better crash protection are even heavier.

[Fschwep]

(1)

Hum... The 2CV was, in fact, designed by a chief engineer from Michelin, during an epoch when Michelin owned Citroën. And it was designed in Clermont-Ferrand, in the French Auvergne region, where people have always been sticklers for efficiency. The 2CV was explicitly designed for poor farmers who had to use it to transport their produce to the market (without the rear seats it would take a grown pig) and drive it on the bad roads and tracks of this mountainous region. One of the anecdotal design constraints was the height: one had to be able to sit in it while wearing a hat - and the chief engineer in question was himself rather a tall man who wore a high hat, so the 2CV has a lot of headroom as a result... ;-)