If you slow a car from 57 to 50 miles per hour (91 to 80 kph), you will get half again better gas mileage. This means that the average American driver would save about $300 per year.
If you slow a car from 57 to 50 miles per hour (91 to 80 kph), you will get half again better gas mileage. This means that the average American driver would save about $300 per year.