Thursday 29 September 2016

Why downsizing and down-speeding set the pace for petrol-driven future

Published 22/04/2015 | 02:30

Citroen Cactus
Citroen Cactus
Citroen C4
Denis Fourchon, chief engineer in charge of Citroen's PureTech Project

OVERALL market figures may not show much of a swing to petrol but within individual segments there are some noticeable little shifts.

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And as the push towards petrol gathers pace, Denis Fourchon, chief engineer of the PureTech Project at the PSA Group, was in Dublin last week to mark something of a turning point.

I spoke with him at some length. Naturally, he believes it is only a matter of time before there is a sizeable move from diesel to petrol.

He was here to talk about the latest PSA petrol engines and, in particular, the turbocharged 3cyl 1.2-litre PureTech in the Citroen Cactus and revised C4.

In both interview and his general presentation he focused on where and how it is all happening.

It all has to do with downsizing and down-speeding the engines. That's where the technology makes it possible to reduce the speed at which the smaller engines work, he said. It is also possible to spread the pulling power across a greater span.

The new generation of turbocharged engines show this when you see the performance figures laid out in detail. The aim is to use less fuel and lower emissions. There is little doubt the gap to diesel in those areas is narrowing.

And because diesel-car prices are usually higher than petrols, justification for buying the former is fading, especially for small-mileage drivers. Of course, there will always be big diesel demand from 15,000+km drivers. We mustn't lose sight of that.

Msr Fourchon is, as you'd expect, enthusiastic but lets the figures speak for themselves. Emissions in the 1.2-litre PureTech in the revised C4, for example, are 40g/km lower than the old 1.6-litre VT; 30g/km of that is due to the engine itself.

He smiles: "It's not so far now when you compare with diesel." The proof of the pudding was in the eating. We had driven the C4 Picasso with the 82bhp PureTech engine earlier. It fits the car well; lots of low-end pulling power which has always been diesel's, rather than petrol's, characteristic.

However, the real eye-opener came in the C4 (which they have just facelifted). Before lunch we'd driven the 110bhp diesel. It was typically . . . diesel. I thought the steering felt a bit heavy. But the 1.2-litre PureTech (110bhp) - which marks the return of petrol to the car - was distinctively better. Quite a revelation really. I would prefer it to the diesel for town driving. On that basis alone, the petrol revolution looks to be well underway.

But we all know there is more at play and stake. Further stringent emission regulations are on their way. Some experts I've spoken to say meeting them will mean an even bigger premium on diesel engines. Denis agrees. Naturally. But he also claims there is still a long way to go with petrol - though just how far is impossible to say.

Engines won't get any smaller; three cylinders is the limit, he feels. However, a wider embrace of technologies, such as hybrid, electric, greater connectivity (to reduce driving times to parking, avoiding traffic etc) will bring substantial improvements. And the hoped-for scale and volume of petrol-engine production would help peg prices.

Petrol is by no means a panacea. We'd be foolish to say that. But it appears that the mid-term future is partly petrol anyway.

Indo Motoring

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