What's all this about?
At an event in Paris Renault revealed some future solutions for motive power, two of them due for production cars in 2015, the other three currently only at the prototype evaluation phase.
Are any of them particularly far out?
One is, but that's one of the prototypes that aren't yet slated for production. So, looking at the others, in 2015 we will see a 10 per cent smaller electric motor from Renault, now producing 88hp and 220Nm, developed and built in-house. And also coming next year will be a three-cylinder turbocharged petrol-LPG hybrid engine, reducing fuel bills and CO2 emissions by 25 and 10 per cent respectively over a petrol-only engine of the same size.
And the prototypes?
One is a mild diesel hybrid for use in commercial vehicles (the 'Hydivu'), another is a small, 'final miles' delivery vehicle based on the Twizy (the 'Velud') and the last is a tiny diesel engine.
Which one of these are you getting your knickers in a twist about?
The last one. It's a two-stroke diesel engine, you see, not a four-stroke as found everywhere else in the automotive world. Two-stroke diesels are most commonly found in marine applications, such as massive cargo ships, but the issue has always been making one small enough to use in a car. Renault has managed to build a minuscule 730cc two-cylinder version it is calling 'Powerful', which is perhaps a little misleading as it currently develops between 48- and 68hp. Torque ranges from 112- to 145Nm, available from just 1,500rpm, and Renault says initial tests are encouraging, although 'the performance needs to be improved' before it could consider introducing it.
What's the point of two-stroke over four-stroke?
Two-stroke diesels have a much better thermal efficiency rating of 50 per cent, compared to a maximum of around 35 per cent for four-strokes, meaning it should be much better on fuel consumption than even the best small diesels of today.
Matt Robinson - 14 Dec 2014