Phil wrote:
How much is such a test influenced by how the car was driven? I have seriously no idea how NOx is measured, but of course typical usage of any type of emission will strongly vary on how the engine is being used - i.e. full throttle, part throttle, under load, in neutral, at N gear, weight of the car, how inflated the tires are, wind or other type of resistance etc.
A test case like conducted by any health and safety or state department can not take into account every single possibility - so a test-case is only here for the sole purpose of comparing every car under the same set of circumstances and where any specific limit applies?
Interesting document on testing procedures (Page 36 onwards) and sampling systems for emission measurement.
(alhtough for a heavy duty vehicle - but I doubt the process changing too much to passenger cars)
http://www.crcao.org/reports/recentstud ... Report.pdf
So in quick summary - a driver with chassis dynamometer experience manually drives a speed load trace that he is trained to follow - without crashing the gears.
So the thing that immediately stands out from this are that
- the test cycles propsed by EPA and Euro themselves are not reprentative of real world driving.
- does not take into account the gradient of the road, among many things (drag, ambient weather condition (affects inlet manifold temps), auxilary systems on engine etc)
Dr Tate, whose work is funded by the Department for Environment, Food & Rural Affairs and local councils, has been monitoring diesel emissions on Britain’s roads for five years and has recorded more than one million cars.
Interesting Dr. Tate's work was funded by the Department for Environment, Food & Rural Affairs - I wonder if they have bothered to look into and strictly regulate Nox from the agricultural industry and due to over fertilizing.