Before the engine even reaches the car to set the official figure, it is first fully tested, calibrated and optimised for economy and CO2 on various test benches and in lab conditions. At this point, it’s ready to go in the car.
The cars used are proper models rather than anything trick, although the Qashqai I was in was covered in camouflage wrapping because it had yet to be revealed to the world.
The test, which is called the New European Driving Cycle (NEDC), happens on a rolling road inside the lab that monitors the speed, weight and resistance. Hooked up to the exhaust pipe is all the equipment to monitor the emissions. The test is done from cold and the lab usually has an ambient temperature in the mid-20s.
Those ‘driving’ it are real off-the-shelf humans, preferably ones with a feather-like touch of the controls and who hadn’t gone back for seconds in the canteen at breakfast.
The NEDC test includes four urban phases and one extra urban one. It is controlled and is always the same, with certain speeds having to be hit along the way, certain gearshifts made at precise moments, lots of coming to a halt and orders having to be followed on how long the acceleration and deceleration phases take.
Engineers do this test 48 weeks of the year to eke out improvements to the official published figure. Clearly they have to do it before the car goes on sale, but there is otherwise no deadline or set time when it must be done; the final figure might be hit in the second, ninth or 44th week of testing.
I had a go at driving a 200-second phase of an urban test that lasts for 1180 seconds in total. And I didn’t do very well.
It’s like playing a really hard game of space invaders with your feet; you are not allowed to touch the steering wheel and you must follow instructions on a screen for pedal inputs and gear changes. A green line tracks across the screen with those instructions you must stick to. It is weird.
The test requires your senses to be retuned as it bears no relation whatsoever to real driving – your ears will be telling you it is time to change gear but the screen is your master, and you can’t shift until it tells you. Which, as just one example, is why gear ratios are so often tuned the way they are: to maximise the performance in the test.
So, how did I do? “Not a bad first attempt” was the rather polite appraisal of the engineer sitting alongside me. He promised to let me know my results. Two years later I’m still waiting, so I assume he’s sparing my blushes.
Hopefully that’s cleared up a few myths around the test. But it won’t have made any difference to what you’re thinking: the test, whatever the intricacies of what goes on in the lab, bears very little relation at all to real-world driving. That’s why it must be changed.
Read more on the Volkswagen emissions scandal:
How the Volkswagen story unfolded
How VW's 'defeat device' works
Top VW bosses to leave
European cars are affected, says German minister
PSA Peugeot Citroën leads calls for tougher emissions test procedures
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