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All Tests
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  Exhaust gas/consumption tests

This NEDC cycle favors vehicles with start-stop systems.

Emission tests have a history and we want to trace it here. No, we leave out the foreign cycles until we come to one with these harmonized test. More on that later. So we are initially moving within the borders of the EU or even earlier of the national states.

Because consumption has always been measured and stated in sales brochures. Attentive motorists have not lost sight of their consumption for a long time, as apart from all thrift it also indicates the well-being of the engine and even a little of the entire vehicle. So it's not always about minimization, but often about comparison.

If the new car consumes more than the old one with the same driving style, then you feel somehow uncomfortable. Something like this can even lead to an immediate sale. Comparisons with oneself are really the most useful. It becomes more difficult with others because the mentalities and the knowledge about the influences on fuel consumption are so different.

In addition, at least for a long time, brand consciousness was sometimes as great as we know it today almost only from Tesla fans, who cannot necessarily be trusted when it comes to consumption or range. So unbelievable ranges are possible, depending on how dynamically you handle a car. Even with the same speed in two adjacent gears the consumption can differ by up to one liter per 100 km.

The need for standardization, e.g. DIN 70020, arose early on for comparison. And here the influence of the vehicle manufacturers becomes clear, because this standard only specifies a constant speed of 90 km/h at which consumption must be measured. We will come to possibilities of manipulation such as here, e.g. with tire pressure.

It was the beginning of a long enmity between particularly low values in the prospectus and rather disappointing practical experiences. The DIN 70030 from 1978 is the driving cycle 70/220/EWG from 1970 implemented in German legislation. In the NEDC cycle shown above, you can still see it as an urban cycle that has to be completed four times.

This was interconnected with the speeds of 90 and 120 km/h to form a so-called third mix (picture above). For the first time, three values and the combination were named by the manufacturers. The extension of this test standard is the New European Driving Cycle. This is where the little meaningful constant drivings comes to an end.

From 1996 onwards, it will even ensure that vehicles with internal combustion engines comply with the applicable emissions regulations even when they are in operation. That is the actual milestone in the measurement of vehicle behavior, because now the complete test drive on the test bench is to be completed. Back then, at Opel we were shown two rack lengths of file folders in order that we see how much loopholes are now being localized.

They had to build a tower-like parking facility to keep the vehicles at a uniform temperature of 20°C for 24 hours. The curves were driven on the various test benches in the majority by (student) assistants. On a monitor directly next to the open driver's window, a type of roadway leading diagonally upwards to the right could be seen.

Of course, it wasn't a road, but the dashed center line represented the acceleration to be achieved and the green zones on both sides the tolerances of the deviations that were still permitted. If the test subject accelerated too much or too little and left the green field, the test was over because the prerequisites for a repetition were now missing, e.g. the right engine temperature. Incidentally, even the speed and duration of the switching operations was prescribed.

The test bench test is repeatedly emphasized in the description of the NEDC, but not the almost equally important coasting test beforehand. Such tests have existed for much longer than exhaust gas or fuel consumption tests. By the way, everyone can do it themselves with their car and find out whether something, such as the brakes, is rubbing too much.

When I last changed my vehicle, it was interesting that the progress in the smooth running of wheel bearings was clearly noticeable. Back to the coasting test, which is said to give more information about the air resistance above 50 km/h and below that more about the rolling resistance. So you ensure a certain speed up to a measuring point and then let the vehicle coast to a halt.

You guessed it, the longer the distance to standstill, the lower the rolling or air resistance. If you record the speeds that are partially measured, you can also easily distinguish between the two resistances. It is important, however, that these values are converted to the torque acting against the drive wheels; the shorter the distance, the more the vehicle has to work on the test bench.

Here you can already guess how important the coasting test is for the performance of the respective vehicle. So if the CO2 values in Europe fell from 161 g/km in 2005 to 118 g/km in 2016, it might also be because the manufacturers were getting better at handling the test procedures. Take Spain, for example, where a test track is said to have been built with the gradient just allowed. he gratitude of the gastronomy there because of the many test teams from all over Europe is certain to the politics.

Yes, you can certified test somewhere in Europe, which then applies across Europe (see E1, E2, E3, etc.). That was just only a trick to get better values. Politicians hardly stand a chance against so many engineers (and lobbyists). Later you heard about targeted masking, not just the joints on the vehicle body, special low-resistance tires and, of course, high tire pressure. All measures that extend the coasting distance.

Finally, here is still a trick for the test bench. Because the vehicle is stationary, it has to move rollers with its drive wheels that are as similar as possible to the mass of the vehicle. If you look at the range of possible curb weights plus driver, then this can only be done in stages. Assuming increments of 100 kg, every vehicle manufacturer will prepare their car so that it comes just under the next limit of 100 mark.

In contrast to the two-year general inspection, for example, the exhaust gases are not analyzed as they flow out, but collected and then determined from the partial quantities. You can confidently assume that the price will be at least a hundred times higher. This is felt by all those who make major changes to engines and have to get them through type approval. Incidentally, even then not only exhaust gases were collected, but all vapors from the respective vehicles.

One reason why water-soluble paints came into circulation so quickly was probably the fact that the paint from that time turned out to be particularly conspicuous in the measurements. Needless to say, the initial temperature was soon significantly reduced. In the meantime, the car has to be put on the test bench at -7°C without forerun.

At the time, of course, we asked ourselves why robots weren't used on the test benches. There was already one of these during the 80,000 km test, earlier probably only for US exports, now also for Europe. All components are marked and now even monitored so that nothing can be exchanged, repaired or readjusted during the test phase. In the end, the test values of the new vehicle must probably be reproducible with a certain narrow tolerance.

Roller dynamometer even for all-wheel drive vehicles

The Worldwide Harmonized Light Vehicle Test Procedure (image) is now based on statistical values from 14 countries of 750,000 real road kilometers. It is about 25 km long, takes about 30 minutes and goes up to 130 km/h with an average of 47 km/h. After all, this test now also applies to Japan and China, but not to the USA.

All models on the market will soon have to be tested according to WLTP, which is currently causing bottlenecks. However, you can convert the achieved values of a vehicle to variants of the same according to certain criteria. But then the CO2 value, for example, is also signposted depending on the equipment.

And what is now referred to as the 6d emissions standard? As usual, everything is initially determined on the test bench. For the exhaust gas values apart from CO2, there is also a standardized, long road test with a mobile backpack that does not measure quite as precisely. The limit values at 6d Temp(rary) must be multiplied by 2.1 and one year later at 6d multiplied by 1.5.

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