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Renault Optifuel Lab offers 13% diesel fuel savings...Biglorryblog tells you all about the slippery Gallic streamliner!

  • 19 March 2009
  • By Biglorryblog


And so on Tuesday it was off to Lyon and the Renault Trucks ( test track at La valbonne to get up close to this magnificent super slippery beast--the Optiful Lab Premium tractor and trailer. As first revealed on Biglorryblog back in December, after doing all the computer modelling of its aerodynamic performance the French truck maker has been busily putting theory in to practice with real life road trials of the Optifuel Lab outfit---which has shown itself to be 13% less thirsty than an equivalent 450hp Renault Premium Route DXi tractor and trailer which was used as the 'reference truck' around the same 400km on-road test route---or to put it another way the Optifuel Lab uses 4.5lit/100km and produces 120g less CO2 for every kilometre it covers...lonewopti097.JPG

At the front of the Optifuel Lab is this extended (by 300mm) streamlined GRP nose and wrap-around bumper while at the back of the trailer is an extra 700mm deep collar as seen below. The Lamberet trailer roof also has a slight bow on it to accentuate the ideal water-droplet profile--though not nearly as much as an equivalent Don-Bur Teardrop---due to the continental height limit. And you can read my full report on Optifuel Lab in Commercial Motor soon. 


Renault has also raised the height of the Premium cab to 4.16m and provided it with an extra deep cab collar and side deflector system which ensures a really tight coupling gap and close blending of the trailer into the back of the tractor too as you can see in this photo..


Throw in the latest Michelin green energy tyres, side valances on the trailer plus an under-trailer dam and the front and clever 'diffusers' on the rear of the trailer side skirts (as seen below) borrowed from Formula 1 designs...


and you can see that this Optifuel Lab is more than just a fancy styling exercise. In order to minmise wind-drag Renault's engineers have really gone to town looking at every element--including the drag created by a large mirror cluster on either side of the cab...


And they have replaced them with these small arms holding video cameras...only how long they'd last in a tight peage on a French motorway or in a gantry wash I didn't like to ask.


Inside the cab each A-post has two screens for the driver, the top one displays the view from a wide angle camera (like a wide angle mirror) while the bottom screen shows the normal 'big' mirror view, albeit in landscape format. The one hanging from the ceiling is for the reversing camera at the back of the trailer. There was also a kerb camera. Despite my lack of French, sitting next to Renault's test driver as he took me around the test track (we journos weren't trusted with driving it..oh no!) he seemed happy enough with the set-up.


As you can see the view is pretty good. Now click through here to learn how the French journos got somewhat grumpy about the Optifuel presentation and how BLB kept his head down....


After letting us take our snaps the Renault people herded us all back into a small presentation room where they kicked off the powerpoint show. Things were all progressing nicely until they started talking about how they had optimised the Optifuel Lab's driveline (with a faster back axle, some engine re-mapping to deliver a bit more torque lower down the rev range and a semi-synthetic engine oil---all of which seemed all very logical to me as the object of the exercise was to see how much further you could improve a standard Premium) when a number of my fellow European journos including, ironically, a couple of French scribes, started to get rather grumpy about Renault's test procedure. I kept my head down and looked on somewhat bemused as frankly we wouldn't have done it any differently on Commercial Motor...and as the only Brit I felt I should show some stiff-upper lip dacorum!


For the record the two trucks (Optifuel and reference artic) did a number of circuits around a test route used (ironically) by French truck magazines with a 5 min interval separating the two rigs. At the half way stage the drivers also swapped truck; moreover, each Premium had an Optidrive auto box which was left in full auto mode through the test runs, thereby further removing any differences in driving style. The runs were done in a variety of weather conditons and the average improvement for Optifuel was a 13% saving in diesel. The fuel was also measured by tank-to-to-tank-top with fuel meter readings taken for each section--again how we do it on CM

Quite why some of my fellow journos got so hot under the collar is a mystery to me. I THINK it might be because Renault had done extra stuff to Optifuel, rather than just test all the aerodynamic stuff in isolation. But as the voices were raised higher I kind of lost the thread (not to also say the will to live as I'd got up a 04:00hrs to get an early flight and by then I was getting a headache). As far as I can see the whole point of the exercise was to see how much better you could make a regular production truck... Naturally it died down as quick as it flared up leaving yours truly wondering what all the fuss was about...and what was for lunch....