Blog: Low CO2 gives you wings
Glenn Brooks | 5 December 2011
Drag-lowering, Renault says
Back on 15 September, I blogged about some mysterious pieces of plastic I spotted attached to the sides of the new Civic diesel. Today I noticed aero add-ons in a similar place on a low-emissions Renault. So what do we think: function or fashion?
Here's a shot of the rear of the Clio Expression Eco dCi 88 which I drove at a Renault event this afternoon. The car has an admirably low CO2 average of 94g/km, something which was once fairly amazing but is now becoming commonplace in the supermini class. And if you're wondering about the 88, it's horsepower (DIN).
But back to my cameraphone-snapped pic. I asked Jeremy Townsend, Renault UK's well-informed director of Communications why each side of this Clio's rear window spoiler has a pronounced bump emerging from it. He maintains that these tiny aero addenda play a small role in lowering wind resistance, confirming that only the Eco dCi 88 variant has them. Sceptical? I was too. So let's look at some facts: thanks to various modifications, the European Commission's test rates the Eco at 78.4mpg on its EC Combined cycle versus 70.6mpg for the standard (106g/km) dCi 88 Clio.
Well, it does then seem as though both Honda and Renault's wind tunnels have found the same way to get the tiniest improvement on an already super-low CO2 number. If you're still sceptical, consider this, which is what I have done: ask yourself why a manufacturer would go to the trouble of adding those little winglets? I have concluded that they're a tweak, and that they probably do work.
Speaking of the quest for a top-notch CO2 number, I've been driving a new and small-engined version of a large-ish car over the course of the last week, courtesy of Vauxhall. Will publish my thoughts on the '2012' 1.4-litre Insignia in a few days' time. But in short, this heavy estate is a really good car that's been saddled with too tiny an engine and gear ratios that are too long. The blame lies not with Opel's engineers but with the CO2-based taxation system which exists in so many European markets. And with the first Euro 6-compliant models already with us, are we about to see a steady roll-out of otherwise good cars troubled by too-small engines?
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