There are $112$ non-isomorphic $6$-vertex planar connected graphs, $81$ of which are $3$-colorable.
I'm searching for one example of an ($n\geq 6$-vertex planar connected graph:
a) that does not contain an even-vertex wheel graph: (W4, W6, W8, W10, etc.)
b) whose vertices are not $3$-colorable
I know that there are plenty of examples, but I can't come up with any.
Here's a generated image of all 99 planar connected 6-vertex graphs:
The non-colorable ones have been painted with red vertices. None of them satisfy condition a).
And, there's an image of all 112 (possibly non-planar) connected 6-vertex graphs (note that the enumeration does not match):
Even here, I can't find any graph that satisfies both a) and b).
So, for $n=6$, there's no such example. For $n=7$, I found several, including these beauties: