The Extended Fish Hook test measures the transient handling properties of a vehicle at limit handling conditions. The test is similar to the standard Fishhook maneuver but shows more steering activity. This test is used to assess a vehicle's roll stability by exciting it with the most critical steering input. It should be noted that the most critical steering input is vehicle dependent.
The given excitation is an open-loop version of a double-limit lane change. It determines which input is needed to exceed a vehicle's roll limit. This input is defined by the steering amplitude scale factor, frequency, and the amount of added roof load needed to exceed the roll limit. Vehicles can then be classified by the amount of amplitude (at a certain frequency) and roof load. The higher the required amplitude and roof load, the better the vehicle.