How many cars actually meet their fuel consumption claims? I am sure there is a disclaimer somewhere stating buyer beware.
What VW did (despite what the NRMA spokesman kept saying on Friday and Saturday that a 'device' had been attached) was add a sub-routine to the engine management software.
It was very simple as all vehicle tests for emissions etc are done indoors with the vehicle on rollers. To achieve a certain speed they set the RPM at a specific number. It's the same if you ask for your speedo to be checked for accuracy at a service BTW.
The sub-routine runs continuously, not just added to vehicles supplied for testing, to detect when the vehicle has maintained the exact RPM for a certain length of time (seconds). It then assumes that a test is being run and recalibrates the engine management to run on low-emissions mode until irregular RPMs are detected. All emissions testing follow a fairly standardised approach and this detection method works well.
WHY THIS MATTERS?
When you are driving on the road there are multilple factors at play such as wind/cross winds, road surface, road incline/decline etc. The engine RPM changes constantly despite your foot being in the same position on the pedal.
How they came unstuck was that the private testing was done to see if the claims matched reality. So they attached the emissions testing equipment to the car exhaust and drove on the road IN ADDITION to lab testing. He did this for 3 makes of vehicle - not just VW.
All three makes had similar bad results - the on-road testing showed much higher emissions than his lab testing did. VW was the worst by roughly twice what the others were above their lab tested figures.
What is strange is that only VW has been singled out here. The other two brands have not been mentioned despite it appearing they also have a case to answer.
It is quite possible that ALL makes engage in this deception, for example with VW their is a long history documented about past 'issues'. The 'issues' have not received publicity before though.
