It’s a petrol engine, but not as we know it! The Insignia will be the first Vauxhall to be fitted with a revolutionary new power unit.
It’s called Homogenous Charge Compression Ignition (HCCI). And the technology combines an oil-burner’s fuel economy with the smooth, free-revving character of a petrol motor, courtesy of some clever engineering.
Standard diesels don’t use spark plugs. Instead, they compress the fuel and air mixture until it’s hot enough to burn by itself. Engines fed on unleaded, however, need a spark to get the process going.
The HCCI system redirects some of the exhaust gases back into the combustion chamber, which warms up the petrol and air mix so that it doesn’t need a spark to ignite. Up to half throttle and 3,000rpm – typical conditions for driving in traffic – the engine works in HCCI mode with huge gains in efficiency.
The rest of the time, if the driver is accelerating hard, it automatically converts back to a conventional spark ignition set-up. That results in a 15 per cent improvement in efficiency. Expect to see this engine offered in the Insignia from early next year. GM has been working on HCCI technology for more than a decade, which is long enough to produce a working demonstrator.
And you can click here to read Auto Express' first drive of the pioneering powerplant.