I wondered that too, since this car has a Japanese license plate (love the license plate frame BTW) you'd think the steering wheel'd be on the right, but I don't see one in front of Rin. I believe that Kayo-chin's supposed to be leaning on the steering wheel & the artist simply didn't draw it in...it looks uncomfortable for her crossed arms to just float in the air like that ;-)
So, basically, they have a left-hand drive car, in Japan.
Yeah, it's hard to spot, but I vaguely see the steering wheel, her forearms are just covering most of it. Look between Hanayo's fingers on the right and under her elbow on the left. Weird to have a left hand steering wheel, but hey! :V