The wii u gpu (radeon part) is either 176 or 352 gflops according to the strip down however there is also the original wii gpu in there and other elements to support wii compatibility. The fact is the wii u gpu is on a cheap 40 or 45nm fabrication process but is not consuming enough power to be 352 gflops so its highly likely to be 176 gflops but that still means its far superior to the 360 as there are many generations of improvement, improved feature set and 32MB of blisteringly fast memory available. Whatever it is 176 or 352 gflops no one is claiming the wii u gpu isn't superior to ps3 and 360.
The big issue is the cpu, we know its a triple cpu identical to the original wii cpu but running at 1.25ghz. It's a basic 32bit risc processor from the last century and doesn't compete in performance with 360 or ps3 because those consoles while having slightly less performance by mhz run their cpu's at 3.2ghz not 1.25ghz and so its an easy win for them.
That brings me around nicely to my final point and that is Project Cars is clearly a racing game with very high cpu requirements because they are taking car simulation to a higher level. This is where the wii u is poor. You can't just downgrade the wii u's graphics to 480p and sort it because the wii u simply hasn't got the cpu resources to run the game. It seems likely to me that the wii u gpu is probably fit for purpose but the cpu can't cope. The ps3 and 360 probably can't run it due to memory requirements and the wii u can't because of cpu requirements.
The wii u version may have happened if they hadn't abandoned the ps3 and 360 versions. Then all 3 powerpc consoles could have justified development. Yes it would have been simplified to the weakest part of each console but it could still have been a enjoyable title for those 3 consoles.
It never made any commercial sense to just release it on wii u in addition to all the x86 versions.