Progress and limits of downsizing Over the past 15 years, the diesel engine has made much progress: "it has reached almost its optimal level today", assures Philippe Mallet, diesel motorization specialist at RENAULT. "We can still gain 5% consumption, through improving its working level. "
As for petrol motorizations, they have greater potential for progress, "between 15% and 40%, provided that the engine size is reduced and that direct petrol injection and supercharging (turbo) are systematically adopted", reckons Hervé Mathieu, petrol motorization specialist at RENAULT.
However, the limits of downsizing will soon be reached. These are firstly physical: "difficult to go below 350cm3 per cylinder, unless you’re using micro-mechanics", considers Mr Gagnepain at ADEME.
These extreme measures will be almost attained by the next generation of 2- and 3-cylinder engines planned at RENAULT, PSA and Fiat.
So the peak of downsizing will be obtained. What follows will depend on the economic limits of investment: the technology necessary for the development of downsizing is costly and, according to economic models, proves to be more difficult to secure a return on.
Petrol bounces back With the arrival of new technologies, efficient in terms of C02 reduction, petrol engines should become increasingly attractive.
At RENAULT "we’re anticipating a stabilization of the petrol/diesel mix and, in particular, a strong resurgence of petrol for small vehicles; with a balancing of sales of between 40% and 45% for petrol (currently 35%), between 45% and 50% for diesel and between 10% and 15% for electric by 2015".
Thanks to downsizing, the petrol engine is therefore regaining credit compared to diesel, whereas it had almost disappeared from certain categories.
It should also be able to benefit from forthcoming anti-pollution standards which threaten to penalise diesel engines more, as they are more difficult and costly to clean up.
Another auspicious factor for petrol: the emerging hybrid technology for
the type of motorizations that work in tandem with the battery-powered electric engine.
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