My point about mario kart 8 textures which is true of many cartoon graphics games especially wii games like mario galaxy and mario kart is they are hugely repeated in each frame and distant objects simply lose texturing and become a single colour. This is so much easier to render than realistic graphics.
The dreamcast only had a gpu capable of 1.4 gflops but did have tile based rendering. It could do cartoon graphics like this for racing games;
https://www.youtube.com/watch?v=GanNn3fmiVA
For realistic graphics it was terrible and completely uncompetitive.
Sonic transformed does have some ambitious graphics, with more complicated texturing than mario kart 8. It also has more detailed car models. Don't use the wii u for comparison though as that only runs at a low 1024x576 resolution, use the ps3's 1280x720 resolution. I've got both wii u and ps3 versions and both suffer from frame drops. I believe the 360 frame rate is more stable of the three. The game looks utterly fantastic on my projector, a feast for the eyes at 720p on ps3 or 1080p 60fps on pc (my projector is only 720p).
Even on these youtube videos I can see there are parts of mario kart 8 graphics that look more primitive although the overall effect of the graphics is excellent.
https://www.youtube.com/watch?v=ndxNhlWXXoY
Anyway at the moment we are trying to make comparisons when we haven't really seen mario kart properly just videos. Too much hype at the moment.