The Yukarimobile (ゆかり車Yukari-guruma) is the highly feared vehicle usually driven by Yukari Tanizaki, and owned by her parents. It is a silver Toyota Corolla, large, expensive and fancy, but Yukari has turned it into a wreck which at first glance makes people wonder whether it has been in a car accident. Due to Yukari's nightmarish driving skills, it has emotionally scarred several people, especially Chiyo (who has even developed a car phobia thanks to her teacher). Other people who have had the misfortune of riding with her include Osaka and Kaorin. The only one besides Yukari herself who actually enjoys being in the car is Tomo, possibly because of the similarities in her and Yukari's personalities.
The fewer deaths, the better, don't you think?
— Nyamo's explanation as to why only two people can ride in the Yukarimobile at once
Yukari's driving is first mentioned when she is hanging out with Nyamo, and says she practiced driving with her dad's car a while ago, but when she hints that she crashed the last time she drove, Nyamo won't allow her to drive, much to the disappointment of Yukari.
When the girls are about to go to Chiyo-chan's summer house, they have to split up and only three people can ride in the less dangerous 'Nyamobile'. Chiyo and Osaka are forced to ride with Yukari this time, and afterwards, Chiyo is shaking from terror.
Does she speed? Well … Sometimes she drives really fast. But sometimes she drives really, really slow. Yukari-sensei needs to pay more attention to her side mirrors. And also her rear mirror. Sometimes I think she doesn't notice traffic lights or pedestrians …
Sounds like she doesn't know how to drive at all.
In order to avoid the Yukarimobile, Chiyo makes her father rent a big car that everyone can fit inside. Nyamo seems grateful for this. Much to Chiyo's horror, Yukari announces that she will be driving. In response to this, Chiyo pushes her away from the driver's seat.
Suddenly I can appreciate how a roller coaster doesn't have collisions.
The third time the group are about to go to Chiyo's summer house, Kaorin joins them. Because of this, they have to take two cars again. Chiyo-chan goes straight to Nyamo's car at once. When Kaorin says that she gets carsick easily, Sakaki agrees to ride in the Yukarimobile, but Kaorin decides to go with her anyway so that she can be with her crush Sakaki. Tomo also goes with them and seems to enjoy the experience just as much as Yukari herself. Yukari competes with Nyamo, and when the latter stops, Yukari goes on driving, only to discover that she ran a red light. Then she notices that her side mirror had been folded in the whole time she was driving.
Despite everything, Yukari seems to really enjoy driving, though it is often questioned if she even knows how to.
All the main girls (including Kaorin) get to ride in the Yukarimobile at least once, except for Kagura and Yomi. Since Nyamo usually drives her own car, she is spared from the experience as well.
Due to how scarred Chiyo was and the way the car was presented in episode 22, it can be argued the car is the "main antagonist" of the series.