SECTOR: MPV PRICE: From €27,000 (approx) FUEL: 4.1l/100km CO2: 109g/km

GM’s European operation revealed a variety of new products at the recent Frankfurt Show, from the Opel/Vauxhall Monza concept, to the eagerly awaited 1.0-litre three-cylinder petrol engine developed with SAIC of China, that will make its first appearance in the Adam.

This advanced petrol engine is the first in a series of related engines and the same is true of the new 1.6-litre common-rail diesel engine that first appeared in the Zafira Tourer in May and is gradually being rolled out in the same car across all GM's European markets. It will follow in other Opel/Vauxhall products in due course, likely to include Astra, Insignia and Meriva.

We gave details of the engine in the May issue – it is only offered in Euro6 form and will trigger a rationalisation of the Euro6, 2.0-litre CDTi range, currently available with 110hp, 130hp, 165hp and 195hp, overlapping with the 136hp/320Nm 1.6-litre engine. GM has not discussed other power output options, but it seems likely that it will be offered with at least one other lower rating to take over from the 110hp 2.0-litre engine.

The Euro6 rating means it is the first diesel from Opel to need the AdBlue fluid additive to help reduce emissions of oxides of Nitrogen (NOx). GM reckons that, depending on driving style, the Zafira Tourer 1.6CDTi will cover between 4,000km and 8,000km before the AdBlue tank needs topping up. Vauxhall and Opel dealers will sell 5-litre top-up packs designed to provide spill-free fill-ups. The filler is located next to the fuel filler under the filler flap with a smaller diameter neck and blue filler cap. Not all Vauxhall and Opel models fitted with the engine will need AdBlue, but expect all the heavier and more powerful models to need it.

When the remaining AdBlue range is around 1,500 miles, a warning light will show on the instrument panel. If the tank has not been refilled with around 800km range remaining, top speed will be limited to around 100km/h, then 50km/h with about 400km range remaining. If the AdBlue tank is run dry, the engine will not re-start after about the fourth attempt, to comply with the Euro6 legislation. So drivers should get used to topping up when the warning light first appears. Fuel stations across the EU will almost certainly be stocking AdBlue too, as many truck fuel stations do now.

GM claims some fairly impressive fuel consumption figures for the Zafira Tourer with the engine – 4.1l/100km combined – thanks to reduced friction in the engine as well as the thoroughly modern design. On the road, it is notably more refined than models with either of the current 1.7-litre (which it will replace) or 2.0-litre diesels. At cruising speeds in sixth gear, it is exceptionally smooth and free from the low frequency rumble associated with so many diesels. Brisk acceleration with higher revs gives a more diesel like sound, but it is muted and not the harsh sound of a revving diesel from a few years ago. The reduced friction is also noticeable on the road. After a downhill section, the road continued uphill and it took far longer for the speed to drop running uphill without power than expected. Driving on the overrun like this also triggers the brake energy recuperation system, reducing alternator use when under power and helping to save fuel.

In "Eco" mode, our test Zafira Tourer’s default setting, power is limited to cut fuel consumption, but prod the Eco button on the centre console and the torquey engine shows its impressive capabilities. Stop/Start is standard on all Zafira Tourers fitted with the engine, not just the ecoFLEX models.

Verdict:

Without doubt, this is one of the best 1.6-litre diesels available and the best four-cylinder GM diesel so far. It will improve the fleet appeal of the company’s cars.