I'll make one last post on the matter.
I know my claim is bold, but my point is in regards to production vehicles. The engine is selected then the gearing is selected to achieve whatever metric is most important.
Example below, very similar vehicles with different engine sizes getting nearly identical fe. Unless yall are theorizing or daydreaming about building a custom car, I stand by my claim: engine size is NEARLY irrelevant for real world fe.
Example:
2020 models, 4dr non-hybrid, naturally aspirated
Honda civic 4dr, 2.0 cvt, 30/33/38
Nissan versa, 1.6 cvt, 32/35/40
Toyota camry, 2.5 8spd, 29/34/41
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