One new unit has already debuted in the new Cascada convertible and more petrol and diesel engines ranging from 1-litre to 2.5-litre are on the way as Vauxhall Opel looks to address criticism of current engines.

Engineers have been working on making big improvements in such things as noise, vibration and harshness as well as fuel economy and emissions.

The new power plants are based on three all-new engine families and will cut the brands' CO2 emissions by 27% by 2020 according to Mike Ableson, vice president, engineering, at GM Europe.

He added: ‘That equates to one million tonnes less of CO2 in that time period. The new engines, along with brand new manual and automatic transmissions that we are also rolling out, are part of our Drive 2022, 10-year action plan.

‘We have taken on board a lot of constructive criticism from customers in terms of our engines and transmissions and we have been working on these new products for the past five years.’

As part of this, the development of diesel engines has been taken inhouse by GM after many years of collaboration with other carmakers including Isuzu of Japan and Italy's Fiat.

With the new engines being rolled out over the next three years, Mr Ableson said the more recent strategic alliance with PSA Peugeot Citroen of France will play an important role.

‘Anytime you have that sort of technical exchange you are going to learn things,’ he added.

As well as the new engines, new manual and automatic gearboxes for low-, mid- and high torque engines are additionally being rolled out. Also under development are new continuously variable and dual clutch transmissions, although Rolf Kruettgen, global technical specialist for manual transmission system performance, said: ‘These are in the pipeline but there is nothing we can announce yet.

‘Certainly in Europe manual transmissions will remain dominant through to the end of the decade but CVT and DCT will gain in popularity. With the new gearboxes we have been concentrating on the smoothness of operation, particularly with the selection of reverse gear.’