If you drive 3000 miles a month, and get 34 miles to the gallon, you are using 88 gallons a month, which is about 360 dollars a month at $4 a gallon.
If you drove an SUV that got 20 mpg, your cost would be $600 a month.
If you drove a Prius that got 50 mpg, your cost would be $240 a month, for a savings over a 20-mpg care of $360, but a savings over a 34mpg car of only $120.
Because was do miles-per-gallon, and not gallons-per-mile, it’s hard for people to compare actual costs. If you drive a 20-mpg car and switch to a 30-mpg car, you will save a LOT more money than if you switch from a 30-mpg car to a 50-mpg car.
On the other hand, I know people who drive more than 3000 miles per month.
My point is that I don’t think that you’ll get 50 MPG strictly on a highway if the car is a gas/battery variety.....it’s still gas on the highway mostly..... and my cost number was from historic remembrance of costs which wasn’t all at $4/gallon.