General Motors is developing a range of diesel-electric hybrid drivetrains that could appear in production Vauxhalls and Opels within five years.
Engineers at GM Europe’s powertrain HQ in Turin are studying the feasibility of integrating the company’s existing hybrid components — motor-generators, batteries and control electronics — with diesel engines.
Everything from mild hybrids to a diesel version of the Voltec powertrain architecture of the Volt/Ampera is on the table, according to GM Europe’s advanced technology chief engineer, Maurizio Cisternino.
“If you want the best fuel consumption, you have to go with the diesel-electric hybrid,” he said. Hybrids are most efficient in the city, while diesels are best for motorways; Cisternino said these theories have been proved through simulations.
Cisternino believes that C and D-segment models like the Astra and Insignia are the best candidates for “more substantial electrification”, meaning the most technically advanced hybrid systems. Cisternino’s team is aiming for a 1000 euro (£880) premium over petrol-electric hybrids, similar to the difference between conventional petrol and diesel cars. But he admitted, “This does not work at the moment.”
GM’s first diesel-electric hybrids are likely to utilise an all-new 1.6-litre turbocharged four-cylinder diesel being developed in Turin (home to GM’s global diesel engine development centre) as well as a special unit dedicated to diesel hybridisation. It will begin replacing existing 1.7 to 2.0-litre engines from 2012, and early prototypes are already running in laboratory conditions.
Programme manager and chief engineer Gianmarco Boretto said the new engine is also a key element in GM Powertrain’s diesel ‘downsizing and downspeeding’ strategy. With more power and torque than the current 2.0-litre unit, the new engine will work effectively with taller, more fuel-efficient final drive ratios. And crucially, the new engine’s electronic controller is compatible with hybrid systems.