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9 Jul 18

90 Opel models are Euro 6d-temp ready

The PSA-owned German OEM is one of the few that took a transparent and proactive approach towards WLTP. Already in 2016, it published the new CO2 and fuel consumption figures of its new Astra – purely informatively, a year before WLTP took effect.

Today, Opel continues down the road of proactiveness and transparency. During the X-Champs event at the Opel Arena in Mainz, highlighting the Crossland X, Mokka X and Grandland X, the car maker announced that in the meantime 90 models have already been type-approved according to the Euro 6d-temp emission standard, which takes effect in September 2019.

That means that both the diesel and the petrol powertrains have been adapted to stay within the NOx limits measured during the Real Driving Emission (RDE) test. The latter came into being after dieselgate revealed huge differences between lab measurements for type approval’s sake and real world driving.

PSA power

The Crossland X (a B-segment MPV-meets-SUV) and the Grandland X (Opel’s answer to the Hyundai Tucson) have been co-developed with PSA. They were in the pipeline long before the German car maker was acquired by the French group, incidentally. As expected, on the diesel side we see the introduction to the Opel range of the acclaimed 1.5 BlueHDi – which is rebadged to simply ‘Diesel’ and replaces the 1.6 EcoTec.

On the petrol side, PSA’s sparky 1.2 PureTech three-cylinder is called Direct Injection Turbo underneath the bonnet of Opel’s models. Indeed, this high-tech petrol engine gets is fuel from injectors placed directly in the combustion chamber, allowing for a higher efficiency i.e. lower consumption. A disadvantage of direct injection is that it causes particulate matter (PM), just like a diesel engine.

That is why it adopts a gasoline particulate filter (GPF), like the majority of petrol engines nowadays. The latter has a 75-percent efficiency rate – compared to over 90 percent in a diesel engine.

Gasoline particulate filter (GPF)

That triggers some questions. Are petrol particulates different in nature and size from diesel PM? The answer given by Opel’s powertrain program manager during an event highlighting the X range of SUVs and the new emission standards was negative. Then why the lower efficiency rate?

“A particulate filter creates back pressure in the exhaust system: they are basically coffee filters that trap the particulates present in the exhaust gases. The smaller the holes in your filter, the more PM you can catch, but the more back pressure you create”, explained the engineer. “Gasoline (petrol) engines are more sensitive to back pressure than diesel engines. That’s why the holes in the filter have to be a bit bigger. Result: a GPF catches less particulates than a DPF. Still, 75 percent is enough to comply with the Euro 6d-temp standards.”

That being said, studies show that small-capacity turbocharged direct-injection petrol engines sometimes emit more particulate matter and NOx than the equivalent diesel model. Worse still, the particles emitted by petrol engines are much smaller – even smaller than a virus, meaning they largely remain undetected, as we previously reported.

NEDC 2.0: higher CO2

A lot has been written about WLTP and how it increases CO2 levels – not in real life, but on paper. To avoid unfair competition and confusion, Europe introduced the correlated NEDC concept. New cars are measured according to WLTP regulations, but their CO2 emissions are back-translated to a virtual NEDC value for comparison’s and taxation’s sake.

Still, these “NEDC 2.0” values are higher than the old ones. One reason is that the new test procedure is stricter than before, eliminating any ‘free interpretations’ of the prescribed cycle and the test conditions. Another one is that the engines have to be recalibrated to comply with the new emission standards, which in many cases means burning more fuel – ironically.

A good example is perhaps the Mokka X. Unlike the Crossland X, the slightly bigger Mokka X has been developed in GM times and sticks to Opel powertrains. Its ancient 1.6 petrol is now being replaced by the latest generation 1.4 Turbo. On paper it should be much more fuel-efficient, but because of the switch from NEDC to NEDC 2.0 it only loses a few grams of CO2. 148 g/km is rather high compared to the Crossland X 1.2 Turbo’s 106 g/km.

The same 1.2 Turbo can be had in the Grandland X, and even wrapped in a significantly heavier and bulkier outfit, it emits just 120 g/km. And there is more good news: this engine can now be ordered with the excellent Aisin-sourced 8-speed automatic. Opel had a surprise for us: we were able to test the prototype version of the latter, the review of which you can read here.

Picture copyright: Opel, 2018

Authored by: Dieter Quartier