It took Toyota around 25 years to perfect hybrid technology and launch it on a series production car. The technology has since migrated into Toyota’s bigger cars (such as the GS and LS executive saloons) with the electric motors hooked up to beefy V6 and V8 engines.

European carmakers, however, have come up with another plan. They are poised to use simplified hybrid technology to allow them to radically downsize the typical engine in larger cars, improving fuel economy and reducing Co2 emissions and pollution.

Such systems are penciled in for future BMWs (including the next 5-series and 3-series) but Saab sources have told Autocar about the system they are planning for an upcoming version of the new 9-5.

Despite being an executive-size machine, the company is developing a 9-5 powered by a tiny turbocharged 1.4-litre petrol engine. This engine will be backed up during periods of acceleration by an electric motor sandwiched between the engine and transmission.