There has been plenty of support for GM’s European operation in the past year or two, and there is no doubt that the announcement by the GM board in early April that it will invest €4bn in its European operations between now and 2016 will bolster confidence in the future.

Part of the investment will fund the powertrain renewal programme that the company announced over a year ago. Three new engine families, covering 13 new engines will be introduced by 2016, renewing 80% of Opel engines. These engines are due to be built at GM’s Szentgotthard plant in Hungary, which can build both petrol and diesel engines on the same assembly line.

We will have seen 23 new Opel models by 2016 too. There will also be new and revised transmissions to go with the engines and IFW has driven a sample of the prototype new engines and transmissions.

The new engines will follow the now familiar trend for downsizing, a process Opel began a few years ago by replacing some naturally aspirated petrol engines with smaller, turbocharged engines.

This process will eventually carry through to a new family of small three-cylinder turbo petrol engines, of 1.0, 1.2 and 1.5-litres, jointly developed with SAIC of China. They will be used in a variety of models from the Corsa and ADAM to the Chevrolet Cruze, but new larger petrol and diesel engines will appear first.

We have already had a glimpse of the new petrol engines in the Cascada, in the shape of the new 1.6-litre Spark Ignition Direct Injection (SIDI) engine. So far, the car has been equipped with the 170hp Eco Turbo variant, but there is also a 200hp Performance Turbo version that will be rolled out across the car range. In addition there will be a 1.8-litre variant of the engine, but this engine is likely to appear without turbocharging for quite specific applications, including hybrid drivetrains.

The 1.6-litre SIDI engine will be available with counterbalance shafts to help smooth the engine, but Opel says that the decision to use these versions will be taken in individual markets.

We sampled a prototype 200hp version in an Astra, around a mixed road route. The engineers working on the project stressed that these were prototypes and development work is continuing. Just the same, the engine seemed smooth, to the extent that at the end of the drive, I asked if this version was fitted with counterbalance shafts. It was not. On the other hand, direct injection engines develop more combustion noise than conventional petrol engines and there was a background noise level, typical of other direct injection petrol engines that can sound coarse when accelerating. Hopefully this is one area where development is continuing. Although petrol engines cannot match the torque output of equivalent-sized diesels, the 200hp SIDI engine pulled cleanly in sixth gear from around 1,000rpm without problems.

GM reckons that the SIDI engines will emit 10% less CO2 – equivalent to around 10% lower fuel consumption and produce around 30% more torque than the current 1.6-litre MPFI turbo petrol engine, while generating 2dB less noise.

Fleets have been very focused on diesel engines, particularly in Europe, where there are CO2 emissions incentives to use diesel, but there are reasons why this might change.

GM has engineered the new 1.6-litre CDTI diesel for Euro-6 emissions. This means that more powerful variants and those in heavier cars such as the Zafira Tourer or the Insignia will be equipped with emissions control systems similar to those used in heavy trucks. To control nitrogen oxides (NOx) in the exhaust, the exhaust gases will be treated using an additive called AdBlue or in North America, Diesel Exhaust Fluid (DEF). It’s a urea-based solution that reacts with NOx to break the gases down into non-toxic gases and liquids.

A few cars from other manufacturers are already using the additive, which has to be carried in a reservoir on the car. For the Zafira Tourer that we drove with the engine, the reservoir will hold eight litres, to avoid carrying too much extra weight. GM estimates that AdBlue consumption will be between 0.5 and 1.0l/1,000km. This means that a full tank of AdBlue will last between 4,000 and 8,000km, so drivers will have to get used to topping up their AdBlue tanks. The filler will be near the fuel filler on the Zafira Tourer and Opel dealers will stock bottles of AdBlue with a filler pipe to ensure that re-filling is as clean as possible.

Under EU emissions regulations, the driver will get a warning when there is only enough AdBlue left to cover 2,400km. If the warning is ignored, the car will eventually go into a “limp home” mode, reducing the power output. If the AdBlue supply runs out, the regulations state that the engine control system must prevent the engine from being started again, until more AdBlue is added.

In Germany, AdBlue currently costs around €0.46/litre. A driver covering 20,000km per year could use up to 40 litres of AdBlue in addition to diesel, so add up to €18.40 to annual running costs, or €1,840 for a fleet of 100 cars. As some fleet management companies have already suggested, fleets will need to factor AdBlue consumption into their operating costs. Obviously this will affect all Euro-6 diesel cars using this technology.

GM will also use a lean NOx system for lighter and less powerful diesel models, which will not need the AdBlue additive. Other manufacturers are likely to adopt similar systems.

If the turbocharged petrol engine was impressive, the new 136hp 1.6-litre diesel was even more so. The engine was fitted to a Zafira Tourer and is made from aluminium to reduce weight. Like the petrol engine it is packed with design features to reduce friction and as a result, fuel consumption and emissions. In the Zafira Tourer, fuel consumption is reckoned to be 4.1lit/100km and CO2 emissions 109g/km. It is capable of taking the Zafira to a top speed of 193km/h.

Engine noise was very muted and even pulling away with 1,000rpm in top gear did not induce excessive noise, or the vibration that older diesels would have produced. Performance is impressive too. There is more work to be done, but we look forward to its arrival in production cars.

Other highlights include a new eight-speed automatic transmission for the Insignia, new five and six-speed manual gearboxes for a range of models and a new five-speed automated transmission. There are dual-clutch automated transmissions to come too.

The manual transmissions have been designed with reduced friction to improve the gear change quality and help to reduce fuel consumption. The five-speed manual we tried was a vast improvement over the current five-speed GM manual transmissions in terms of reduced gear change effort.

Opel has shown it can build better quality cars, now it looks as though they will get engines to match.