[jauntywundrkind]

It's called miles per gallon equivalent. To me, the name is plenty clear & I don't see how one would be confused. Yes one needs to understand the price of those fuels to figure it out.

Miles per dollar would be extremely region specific. And temporally specific; it'd change as prices wax and wane. I don't see how such a MP$e would in practice work.

My understanding is much of the world does kWh/100KM, which by virtue of the constant gives a reasonable straight number. Tesla for example has a page called European Union Energy Label, where we get figures like: Model 3 Rear-Wheel Drive, 13,2 kWh/100 km. It's perceived as more human friendly I guess than .132kWh/KM.

It definitely does seem like having the two units - either 1 gallon or 33.7kWh EPA - makes it really hard for consumers to understand the relative merits of their vehicles.