It depends on how you calculate and how far you drive at a stretch, though.
Using published numbers:
If you drive 10 miles, you wouldn't use any fuel at all.
If you drive 40 miles, you might not use any fuel at all.
If you stay with the short trips, and recharge in between, you might never use any fuel to move the car.
If you drive for 80 miles, you'd use about 1 gallon of gasoline, and you'd have obviously gotten 80 miles to the gallon, if you are just considering the gasoline used.
If you drive the full advertised ~340 miles on the highway, you might be down to about 38 miles per gallon.
If you drive that same full range with a mix of driving, you might be in the 34-35 mile per gallon range.
If you live where there are enough "free" charging stations, you can drive on the public dime all the time, too. Even though you can afford an expensive car. :biggrin: