He finally did it with this fascinating video on the history of this unusual vehicle:

The 2CV was the car of Pierre des Cieux in The Ten Weeks, but his daughter Madeleine got about in a Dyane (also described in the video.) An excerpt tells of the ride she gave her black classmate James Bennett:

James watched as she walked out from the front door to the street wearing her leather jacket. Looking at the way she was dressed and carried herself, he thought he had been transported into another world. They walked a few metres down the street to the Dyane. James went to the driver’s door; Madeleine unlocked it and waited for him to open it. But he could not get get the handle to move.
“You must pull the handle up to open it,” Madeleine explained.
“This is a very unique car,” James observed. He opened the door successfully and Madeleine got in. He closed the door and went around to the other side to enter while Madeleine started the car. Putting it into gear, the Dyane’s size and manoeuvrability paid off; she was able to get out of her space and down the crowded street without difficulty.
She turned right onto Ocean Avenue. It was chilly; the 10°C temperature, combined with some ocean breeze, meant that the windows were up and the heat was on, and it only began to warm the chilly interior as they came to a stop at the intersection of Melaleuca Street.
James looked around at the car he was riding in.
“You think it’s funny?” Madeleine said.
“Of course not,” James protested.
“Yes, you do,” she said. “Everybody does.” The light turned green and she made a hard turn onto Melaleuca; the soft suspension caught him off guard and he ended up hitting the door.
“It’s not funny any more,” he said while trying to upright himself.
They made it to the Dahlia Bridge. The sun had just set to their left, leaving its dimming light over the western part of Verecunda Bay. The coastline of Collina was receding from them as they advanced across the bridge. Their voyage across the bridge was a leisurely business; the Dyane’s tiny engine wasn’t a problem on the Point or in the city, but on open stretches of road—both the bridge and those in Uranus—its limitations became apparent. They had plenty of time to see the sunset on one side and the city lights of Verecunda on the other. The afterglow of dusk was still visible on the taller buildings of the city, as it was along the coast of the Point leading up to the lighthouse. This scene, taken for granted by the locals, was a wonder to behold. James viewed a scene that he usually missed as he drove himself across the bay. It helped him to forget that he had given up his honour to travel in this tiny car driven by his sudden date.

Her father took possession of the car after she left for Europe, and in The Wetland Way he used it wisely to pick up the Asian Terry Marlowe:

When she got to the portico entrance of the guesthouse, she stopped dead to see Pierre des Cieux standing next to the Dyane that she remembered Madeleine driving. “So now you know why only guests stay here,” he said. “Let me drive you to the Government House and make your journey a little easier.”

“It’s not that far, I can walk,” Terry said.

“Peasants walk, bourgeois drive, but kings and their royal counsellors have a chauffeur!” With that, Pierre opened the door to let her in. Terry realised that he wasn’t going to take no for an answer, so she got in.