How the EPA gets there
With all the hubbub lately about falsified mpg claims and lawsuits pertaining to other Ford/Lincoln offerings I thought it would be a good time to check in on how the EPA comes up with the mileage figures we all weigh so heavily into our purchase decisions, have a look:
In a lab the drive wheels are pulled onto a dyno to simulate driving dynamics.
Driver runs the car through a standardized driving routine attempting to simulate real world trips.
A schedule stipulates the speed the car must travel at during every second of testing
An outlet hose captures exhaust gases and measures them to calculate the amount of fuel consumed.
Things to keep in mind:
Outlet hose measurement cannot effectively capture mileage estimates for Fuel cell, electric or hybrid vehicles
No idle time that simulates red light fuel waste
Vehicles are babied, light acceleration and diminished speeds ( about 50 mph for highway test)
City test lasts 5 minutes, Highway test lasts 12 minutes
City test done with cold engines, Highway test done with warm engines
Looking at this list its very easy to see where gaps in mileage claims can come from...