All bullshit claims.
So let's say the car is driven 50 miles in a day. For the first 40 miles, no gas is used and during the last 10 miles, 0.2 gallons are used. That's the equivalent of 250 miles per gallon. But, if the driver continues on to 80 miles, total fuel economy would drop to about 100 mpg. And if the driver goes 300 miles, the fuel economy would be just 62.5 mpg.