[Graham]

So you run to class max widths - scale has nothing to do with it?

not exactly, there is a statement within the rules to say that the cars must be to 1/32nd Scale.
But as we are running an event with both Muscle Cars & DTM cars split into 2 Classes, there is a overall Event width limit

But I would accept models as being in scale if they are within a reasonable scale tolerance that you get with "most" brands, Scalextric, SCX, Ninco.
However I am not very familar with these Spirit models ?