Editing Citroën 2CV (section)

=== World War II ===
{{multiple image
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| image1    = Citroen TPV four-cylinder engine.jpg
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| caption1  = Water-cooled engine from the TPV
| image2    = Citroen2CV prototype.JPG
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| caption2  = Restored Citroën TPV with a single headlight
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On 3 September 1939, France declared war on Germany following their invasion of Poland. An atmosphere of impending disaster led to the cancellation of the 1939 motor show less than a month before it was scheduled to open.<ref name=Automobilia1940-46 /> The launch of the 2CV was abandoned.

During the [[German occupation of France in World War II]] Boulanger personally refused to collaborate with German authorities to the point where the [[Gestapo]] listed him as an "enemy of the Reich",{{sfnp|Reynolds|2005|p=28}} under constant threat of arrest and deportation to Germany.

Michelin (Citroën's main shareholder) and Citroën managers decided to hide the TPV project from the Nazis, fearing some military application as in the case of the future [[Volkswagen Beetle]], manufactured during the war as the military [[Volkswagen Kübelwagen|Kübelwagen]]. Several TPVs were buried at secret locations; one was disguised as a pickup, the others were destroyed, and Boulanger spent the next six years thinking about further improvements. Until 1994, when three TPVs were discovered in a barn, it was believed that only two prototypes had survived. As of 2003, there were five known TPVs.{{citation needed|date=October 2016}}

By 1941, after an increase in aluminium prices of 40%, an internal report at Citroën showed that producing the TPV post-war would not be economically viable, given the projected further increasing cost of aluminium. Boulanger decided to redesign the car to use mostly steel with flat panels, instead of aluminium.{{sfnp|Reynolds|2005|p=149}} The Nazis had attempted to loot Citroën's press tools; this was frustrated after Boulanger got the [[French Resistance]] to relabel the rail cars containing them in the Paris marshalling yard. They ended up all over Europe, and Citroën was by no means sure they would all be returned after the war.{{sfnp|Reynolds|2005|p=29}} In early 1944 Boulanger made the decision to abandon the water-cooled two-cylinder engine developed for the car and installed in the 1939 versions. Walter Becchia was now briefed to design an air-cooled unit, still of two cylinders, and still of 375&nbsp;cc.<ref name=Automobilia1940-46 /> Becchia was also supposed to design a three-speed gearbox, but managed to design a four-speed for the same space at little extra cost.{{sfnp|Reynolds|2005|p=34}} At this time small French cars like the [[Renault Juvaquatre]] and [[Peugeot 202]] usually featured three-speed transmissions, as did Citroën's own mid-size [[Traction Avant]] – but the 1936 Italian [[Fiat 500 "Topolino"]] "people's car" did have a four-speed gearbox. Becchia persuaded Boulanger that the fourth gear was an overdrive.{{sfnp|Reynolds|2005|p=34}} The increased number of gear ratios also helped to pull the extra weight of changing from light alloys to steel for the body and chassis. Other changes included seats with tubular steel frames with rubber band springing<ref name="citroenet2">{{cite web |url=http://www.citroenet.org.uk/passenger-cars/michelin/2cv/cutaway/siege01.jpg |title=2CV seat design |via=Citroënët |publisher=Citroën |access-date=19 January 2019}}</ref> and a restyling of the body by the Italian [[Flaminio Bertoni]]. Also, in 1944 the first studies of the Citroën hydro-pneumatic suspension were conducted using the TPV/2CV.<ref>{{cite web |url=http://www.citroen.co.uk/our-brand/history/innovation/ |title=Innovation &#124; History |publisher= Citroën UK |access-date=3 December 2011 |archive-url=https://web.archive.org/web/20110320012110/http://www.citroen.co.uk/our-brand/history/innovation |archive-date=20 March 2011 |url-status=dead }}</ref>

The development and production of what was to become the 2CV was also delayed by the incoming 1944 Socialist French government, after the liberation by the Allies from the Germans. The five-year "Plan Pons" to ration car production and husband scarce resources, named after economist and former French motor industry executive [[Paul-Marie Pons]], only allowed Citroën the upper middle range of the car market, with the Traction Avant. The French government allocated the economy car market, US [[Marshall Plan]] aid, US production equipment and supplies of steel, to newly nationalised Renault to produce its [[Renault 4CV]].{{sfnp|Reynolds|2005|p=40}} The "Plan Pons" came to an end in 1949.{{sfnp|Reynolds|2005|p=42}} Postwar French roads were very different from pre-war ones. Horse-drawn vehicles had re-appeared in large numbers.{{sfnp|Reynolds|2005|p=43}} The few internal combustion-engined vehicles present often ran on town gas stored in gasbags on roofs or wood/charcoal gas from [[gasifier]]s on trailers.{{sfnp|Reynolds|2005|p=43}} Only 100,000 of the two million pre-war cars were still on the road.{{sfnp|Reynolds|2005|p=43}} The time was known as "Les années grises" or "the grey years" in France.{{sfnp|Reynolds|2005|p=44}}