Personally, I think that minifigures are underscaled with everything; take minifigure accessories, for example: a walkie talkie is nearly the same height as a minifigure. Small accessories like wands are as long as minifigure legs... my point is, minifigures are small people in a big world, and Speed Champions fits right in.
Hypothetically, if a world of LEGO existed, minifigures would surely decide that, for practicality, width is the most important factor, instead of some idea of needing to be taller than their vehicles. Addtionally, LEGO buildings, both City and Modulars, are a bit... small. Two, three stories, with relatively low ceilings... more "scaled" cars (I understand that minifigure scale is contentious, but I base it on a level of realism for minifigures) are bound to look big next to them, especially the eight wide cars. But, for example, if you were to place an eight wide car next to a large LEGO skyscraper, i think that they fit in really well. You can see that the ceilings are taller, and the numerous floors really create a scale that LEGO couldn't sell in a set.
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Skyscraper build by @wooootles on Instagram
Some more examples:
"Situated in the layout.'
"The last shot before I dismantled my layout."