For a retrofit? Not even Yes!

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Around twelve million Diesel passenger Cars are affected by potential driving bans. To bypass this could be retrofitted with a catalyst. However, the technology is only expected from 2019.


With the decision of the Federal administrative court in February, cities and municipalities now have the possibility to impose bans against older diesel vehicles. In particular, vehicles with exhaust emission standard Euro 4 or below would be affected first. Next, models with Euro 5 will then come off.

Circumvented the ban by the retrofitting of so-called SCR catalytic converters (selective catalytic reduction) to reduce emissions of oxides of nitrogen. Such retrofit systems are currently, according to ADAC, although still in development, but could soon be ready for series production. The most important answers to the Retrofitting of older diesel cars.

What retrofit options are there?

The currently favored exhaust aftertreatment for the reduction of nitrogen oxides are so-called SCR-catalyst systems. In SCR technology the nitrogen oxides produced during the combustion process and are converted, by injection of a urea solution into the exhaust tract in water and nitrogen; the nitrogen oxide emissions are reduced considerably. Such a System retrofit, you need sufficient space in the engine compartment, the urea tank to accommodate. In addition, the SCR has to be connected to the System with the engine control system. Although there are already several providers of such retrofitting solutions on the market, the systems are but at the earliest in a year.

What is the SCR retrofit cost?

The cost for a SCR retrofitting to lie, according to ADAC, between 1400 and 3300 euros per vehicle. The actual price depends on the vehicle and engine type. There is also the cost of installation. Who assumes the costs for the retrofit, is currently still unclear. “The cost of a retrofit should not need to the consumers,” said Christian Buric from the ADAC. “The manufacturers should strengthen the confidence of consumers, by participating at least with a significant contribution to the cost of the retrofits.” Also other possibilities are conceivable. In the past, it was already discussed about a Fund in which the car maker to Deposit in accordance with the number of sold diesel cars in order to Finance the retrofits.

How long does a retrofit take?

For installation, the rebuilder of between two and 15 hours of work. In practice, the ADAC expects, in view of the complex system structure of a SCR retrofitting of with Tank, exhaust system, cables and cabling, and commissioning depending on the type of vehicle, rather with an installation time of at least one working day. Accordingly, the cost of installation.

How effective these solutions are?

In a practical test of the ADAC with different prototypes of SCR systems to the automotive club was able to demonstrate that with Hardware on Euro-5 diesel fuel vehicles of up to 70% and extra-urban are ejected retrofit up to 90 percent less pollutants. Even under poor conditions, the retrofitted vehicles issued still 50 percent less NOx. The car manufacturer offered a Software update should, however, save an average of only about 25 to 30 percent of nitrogen oxides. “The Software Update alone is not enough. Where it is technically possible and appropriate, should also be considered a Hardware upgrade eligible,” says Buric from the ADAC.

Which models can be retrofitted? How many of them are in circulation in Germany?

In Germany, approximately 15 million diesel drive currently cars, around 12 million of them have the Euro 5 Norm or worse; these vehicles would be affected by the possible retrofitting measures. In theory, each of these vehicles can be converted. The older however, the car is, the more complicated and expensive the conversion is. According to ADAC, a tag, therefore, only in the case of vehicles with the emission class Euro 5 of which are in Germany, around six million on – the – go-makes sense. Retrofitting with a catalytic Converter system should be according to estimates by the ADAC in 90 percent of all Euro-5-vehicles. In the case of cars with lower emission classes, a conversion would be mostly not economically viable, since the conversion costs under the circumstances in the respective vehicle value could exceed. Nevertheless, the ADAC intends to work with the legislators to ensure that Euro 4 vehicles are included. “How the aftermarket companies and automobile manufacturers to focus first of all on the offer for Euro 5 Cars and only later, or, at best, offers for Euro 4 limited will develop, it is not yet possible,” said Buric. After all, the Federal office are in the power of travel-around four million vehicles with Euro 4 and about two million Cars, with the underlying emission classes registered.

When can I get my vehicle converted?

Here is the biggest hurdle, because the retrofit systems to reduce NOx emissions are not currently on the market. The ADAC systems tested were prototypes of different rebuilder. “For a standard implementation of a model-specific adaptation of the systems and their testing in the continuous operation required. This requires more development time and, above all, the support of vehicle manufacturers,” said Buric from the ADAC. In the development of retrofit systems, the company would first focus on high-volume models, to be able to cost-effective systems offer. If the rebuilder will be supported by the car manufacturer that could be offered to such systems within a year. According to the ADAC use are ready and approved systems but now the car manufacturers in the shelf. Years ago, car manufacturers, diesel vehicles surcharge with SCR would have sold systems or storage catalysts.

What are the disadvantages of a retrofit?

The SCR System requires, for example, for the preparation of urea, additional energy. The effect on fuel consumption. In the Test of the ADAC, the consumption of cars increased by 0.1 to 0.3 liters per 100 kilometers. In addition, the urea is used up at some point and must be refuelled. The ADAC calls, therefore, for systems with at least ten litres. Depending on the mode of urea would be sufficient for 3000 to 6000 miles. Such a great Tank, however, is not always in the vehicle.

Can I drive with upgraded cars when driving be banned?

So far, the Federal administrative court has decided that driving bans are legally permissible and cities can ban diesel vehicles. Further binding regulations. “With this judgment, it must now be a legal framework that governs Hardware conversion of diesel cars,” says the ADAC-man Buric. Currently, but it is expected that the retrofitted vehicles, entrance restrictions, are excluded. These are also recognized as a clean Diesel would have to get the vehicles, a plaque or an entry in the vehicle registration certificate.

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