According to the magazine Teknikens Varld, which believes the 'moose test' - a test where the vehicle is thrown from one lane to the next and then back to the original lane in quick succession to see how it holds up to last minute obstacle avoidance - is the standard for many manufactures in the industry for sudden evasive maneuver.
Judging from how well Porsche's other models fared in its test, it was surprised to find that the Macan S diesel behaved differently as compared to the Macan's other rivals like the BMW X4 and Range Rover Evoque. The Macan tend to lock up its front left brake which in turn causes it to go straight on longer than usual. In other words, the car spent too much time in the opposite lane hence putting its passengers at a higher risk. Using another identical Macan S diesel produced the same results.
Porsche seemed to have heard about this and has since responded that the lock up of the brakes is part of its ‘Active Rollover Prevention’ (ARP) safety feature. It was intended so that the car understeers slightly when the locking up of brakes occur to prevent unwanted oversteer or the possibility of a rollover.
Read on for the full statement from Porsche and let us know what you think!
The brake intervention shown in the video is a deliberately applied intervention to prevent the car from rolling over. This is called Active Rollover Prevention (ARP). The precise, momentary application of brake force to the front wheel at the outside of the bend down to the low slip range minimises cornering forces to avoid critical or instable driving conditions such as oversteer, rollover or detachment of the tyre from the wheel. Situations such as these may not be controllable by the driver.
The video shows that an understeer response is selected on purpose since it is significantly easier for the driver to control than oversteer. The function shown and the resulting driving response are explicitly desired to increase driving safety in such a highly dynamic driving manoeuvre.
In the SUV segment, Active Rollover Prevention (ARP) is state-of-the-art technology and is also used by other vehicle manufacturers.
The intensity of ARP intervention is dependent on vehicle speed and steering angle speed, among others. This means that ARP brake intervention is diminished accordingly at reduced vehicle speed or steering angle speeds. On the other hand, it means that the driving style adopted by Teknikens Värld was very demanding and resulted in the safety function being triggered.
Active Rollover Prevention is permanently active, irrespective of whether Porsche Stability Management (PSM) is on or off. If PSM is on, ARP intervention is significantly diminished since PSM brake interventions to stabilise the vehicle occur much earlier or are superimposed.
The function (ARP) is applied for a maximum of 300 milliseconds, depending on the driving situation. This short intervention ensures the directional stability of the vehicle. Lateral displacement is negligible. For this reason we do not regard this driving state as critical. As the video shows, lane changing can be completed stably and safely. What is more critical in this situation is if the vehicle were to roll over or the rear were to break away. The vehicle demonstrated none of these instable states (rollover, oversteer, wheel lift) at any time.
Porsche uses a comprehensive dynamics test programme which the Macan completed successfully. The driving manoeuvres performed include double lane change according to ISO, slalom with 10 x 18 metres and 10 x 36 metres, the VDA obstacle avoidance test which is very similar to the Teknikens Värld ”moose test”, and the NHTSA rollover safety test. All Porsche cars are designed for maximum safety based on these and other world-wide tests.
Hermann-Josef Stappen, Porsche