Scenario A. Home commute. Load the preset (~1,000 mi, 10% public). Blended $/mi should sit close to home. Flip mi/kWh ↔ kWh/100 mi and confirm blended dollars do not jump. KWh vs mile, labels do.
If blended cost moves when you only flip units, the bridge is broken. Here it should stay put.
Scenario B. Road-trip heavy. 70% public mix at a higher DCFC rate pulls blended $/mi up. Watch break-even $/gal rise. gas has to get cheaper to “win” against that mix. That is parity literacy, not a morality play about road trips.
Scenario C. Efficient home. Higher mi/kWh shrinks every $/mi cell. Same rates, lower road cost. Efficiency is the bridge width. A colder month that drops you from 4.0 to 3.2 mi/kWh widens every cell again; update the flip value rather than blaming the utility alone.
Scenario D. Rate shock. Hold efficiency and mix fixed; raise only public $/kWh. Blended period cost rises in proportion to public miles. Home-only drivers barely notice; road-trip books feel it immediately. Mix is leverage on the sticker.