There is a phenomenal amount of trivia tidbits associated with  Citroën. Let’s start with the obvious:
Where did the logo come from?
To answer that, let’s go back in time….
André Citroën was a man who always looked for an edge. He wanted technologies that were cutting edge, to keep his competitors at bay. He even looked at Henry Ford’s assembly lines, to glean information that might help his building processes. He kept himself abreast of technologies as they developed. This is how he came across a small Polish factory which had developed synchromesh gearing.

The chevron shaped synchromesh gearing from Poland

Immediately seeing the future in this, he bought the technology. He was so impressed with it, he began using it as the logo for Citroën.
Today, synchromesh gearing is used in pretty well all standard shift cars. Synchromesh gears allow the operator to shift gears without having to “double-clutch” and provides for a smooth transition from gear to gear.

When Michelin took over the reigns of Citroën, They weren’t stupid. They knew André Citroën was on the right track as far as using emerging technologies. They continued with this until the firm was sold to Peugeot in the early 70’s

Which leads to the next trivia tidbit….

Michelin clad all Citroëns with…well, what else, Michelin tires!
Being innovative themselves, the developed a radical concept, the radial tire. The first cars with radial tires were…well, what else, Citroën!

Citroën had a whole office complex devoted to design and innovation, called the Bureau des Études in Paris. The brightest and best were recruited. After the war, the Bureau des Études went into high gear. The 2CV was already into prototype stage, and refinements were progressing nicely. When the 2CV was introduced in 1949, it proved so popular, demand far outstripped supply. Slow assembly was the culprit. The Bureau des Études studied the problems surrounding assembly. One of the consultants hired was my father. His contribution was introduced in 1960. The hood and sides were a one piece affair. Ribbed. The design change was to make the hood and sides into 3 separate pieces.
This way, hoods could be stacked along the side of the assembly line, thus increasing productivity. Along with cosmetic changes, this proved to be very popular with the public, and supply finally met demand.

Citroën was not the first with turning headlights. This honour belonged to Packard. Packard in 1932 or 1933 used the centre link which was mounted on the front of the car to mount the lower headlights. Citroën used the high beam lights. Of course, the U.S.A. did not allow these with Citroën, hence all US models had fixed headlights. Amazingly though, they now allow the Lexus to have them. I suspect they must have wined and dined and lobbied the six-chinned, comb-over Senator Claghorn to allow this. (there is no such Senator, it’s a stereotype)

Anti-Lock braking
Citroën was also the first with Anti-lock brakes. In 1970, the SM was introduced to the world. It was technologically the most advanced car on the planet at that time. It had a rudimentary mechanical anti-lock braking system on the rear wheels. Citroën engineers decided it was more advantageous to prevent lock-up on the rear wheels. They felt it was safer to have a car “ski” straight, rather than fish-tailing  to a stop.

Safety
Citroën was the first auto maker to incorporate safety features in all their automobiles. The Big Three here in North America were convinced that by adding safety items in their vehicles would be akin to admitting the cars were unsafe to begin with. Citroën started by ensuring all cars has seat belts. It went further. Crumple zones, one spoke steering wheels to prevent chest injury in case of collision, break-away roofs to prevent entrapment were more examples.
One of the neatest ideas was the hood. In 1955, with the introduction of the DS, Citroën went away from the side-opening bonnets of the Traction Avant. Engineers worried about hoods flying open while driving. One cannot see anything when the hood flies open and comes to a rest against the windshield! The design team gaves this matter some thought. The solution was simple. The hood was curved where it met the windshield. Hence, should the hood fly open, one can still see through the curvature! Amazing!