I've lived in Germany for 14 years with on and off trips for another few years, the W212 E class was the most common Taxi you would see (this was surrounding Frankfurt) . Mind you, the taxi spec is vastly different from the consumer versions, and the locals that would get into the consumer spec would be amazed at the differences. Similarly, the Sonata used as a Taxi spec feels so different with their lack of an infotainment system or a teeny tiny one, fewer speakers, its 16 inch wheels and cloth seats that I would not be able to to compare it to the PKDM model. The most common taxi I have used was the last gen Camry and I would still swoon over its drive.
Nonetheless, you not liking the Sonata is perfectly reasonable, just wanted to point out the differences in taxi specs!