Fuel Consumption.

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
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Hi everyone,I was just wondering what the difference in fuel consumption is between a Merc Actros cruising on the motorway at 50mph to one cruising at 56mph.My company are very keen on fuel efficiency,and want you to cruise at 50mph,and to turn your engine off when waiting for long periods to conserve fuel.A bonus is that they don’t want anyone rushing around,which I think is very good.I just wondered what the difference would be over a 9 hour shift on fuel consumption figures,on a fair run.

Also,does anyone else have to use the Vemis card system or spy in the cab?I am just intruigued to know.Thanks,
Glenn,

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In real terms Glenn, you would just have to ■■■■ it and see. Manufaturer will give you a specific fuel consution, but it rarely translates in the real world. So, do a week at 50, and a week at 56, remember all motors aint identical anyway, so you need to concentrate on your particular motor, and your driving style. Compare the figures and see for yourself, thats what Id do anyway.

Mal.

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My company is also keen on fuel comsumption, but have not gone as far as telling us to cruise at 50mph(Limiter set at 55 anyway). We have been given individual driving instruction, about always staying in the green band and letting the torque pull the speed up, rather than over revving the engine, also block changing the gears and using the cruise control. They are also trailing some new aero-dynamic kits on tractors & trailers :open_mouth: (any colour as long as it’s white)

We also attended a seminar about fuel efficiency, which gave some facts & figures from other company trails. Some of the saving are fairly dramatic and all go straight to the companies bottom line profits. But the benefits to the driver are less direct, unless related to a bonus scheme. eg: more profitable company = better wages etc :unamused:

www.transportenergy.org.uk/
We should discuss our daily KPL at the end of shift de-breif, but very rarely do :confused:

I personally drive at 53mph on cruise control and find it less stressful, but we only carry light weights, so can maintain a constant speed uphil and down dale. (also play leap frog with the 44t 70mph downhill speed merchants, but thats a different topic :imp: ) and leaves a bit in reserve for overtaking slower moving vehicles.

Havn’t Hanbury Davis set the limiters on there trucks to 53mph :question:

Have no experience with Vemis, but we are on Isotrak. Which is a satelite tracking system. I know they can check where you are at all times, but if your doing nothing wrong, you have nothing to worry about. On Isotrak messages can be sent in both directions, so the mobile becomes redundant. Most of the data has to be imputted by the driver, including driver mode(like tacho), but it has a timer on it, so you can keep track of driving hours(not as sophisticated as Hour Guard) We also have a panic button for emergencies.

From memory doesn’t Vemis record everything including driving style, eg engine revs etc.

Like everything else in this business, it depends what the wonderful/pillocks (delete as required)in the office want the information for :wink: and how they use it :exclamation:

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Glenn:
Hi everyone,I was just wondering what the difference in fuel consumption is between a Merc Actros cruising on the motorway at 50mph to one cruising at 56mph.

When I did the Actors training course they show you a graph of wind resistance versus speed. Its pretty flat until you get to around 50 MPH then it starts to increase exponentially. THey reckon 53MPH is the sweet point for speed vs consumption. You get a bit better consumption at 50 MPH but not enough to difference to make it worthwhile.

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I used to be very fuel consumption aware when i lived back there, but the lower speed / lower consumption thing is infact ‘garbage’

I have a fuel consumption sector built into the computer section of my truck, which I am sure a lot of you guy’s must have, I use it a lot, trying to keep it at the best fuel consumption as I drive by always trying to keep the instant MPG above the Average MPG. When fully loaded (80,000lb) I find that running a 70 mph uses a lot less per mile than running at 65 mph or even lower (interstate figures).
On back roads however with a loaded trailer the consumption shoots up, but is much lower when running empty.

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Agreed, a fuel saving scheme only works when there’s something in it for the drivers. Otherwise, what’s the point?
Minor roads, or ones with lots of junctions will ■■■■ fuel like no tomorrow. It’s speeding up and slowing down that eats it up. A constant speed is the most efficient.
If you haven’t got cruise, sit on the limiter, it’ll do a better job than you will at keeping to 56. You may get a benefit from 53, but it depends so much on the gearbox and engine. Some will do well at that speed, others will be just too low in the rev range to cope with any real hills. Try it in your specific vehicle and see. Do what is most comfortable to you. Drive easy and gentle and you’ll get more results from that than you will from a 3 mph drop. Don’t race.

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The consumption increase from 50 to 56mph isn’t just linked to the 150 or so extra revs that the engine requires to maintain the speed. The key factor is the increased wind resistance from pushing a 4m x 2.49m frontal area through the air at an extra 6mph. Air deflectors etc will definitely contribute to reduced consumption but the same vehicle will still use less fuel at 50 than 56. Throw in the fact that most modern European trucks are geared for 85km/h/52.3mph and 56mph becomes even less efficient.
At a guess I reckon 56 will cost you around 5% more fuel than 50. Of course over certain short routes this may not be the case - the benefit of carrying an extra 6mph through the bottom of a valley before a hill is helpful if you’re running through a successively hilly stretch, but on a typical motorway run such as Exeter to London or Paris to Bordeaux the reduced speed will return better economy.
Whether you can do all you need to at 50mph is another question !

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Another reason 56 isnt efficient, is because the limiter is always fighting the cruise control, so by setting it a couple of K’s under it maintains the speed without battling.

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I was told at the PDA that 56 mph is more efficient than 50/53 mph. One respondent said his boss had their limiters set at 92 km/h (57 mph). They also advocated rolling down steeper motorway hills in excess of 90 km/h and saw nothing wrong with that.

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daveb0789:
I was told at the PDA that 56 mph is more efficient than 50/53 mph. One respondent said his boss had their limiters set at 92 km/h (57 mph). They also advocated rolling down steeper motorway hills in excess of 90 km/h and saw nothing wrong with that.

On the first point, EU Regs require the limiter to be set at 85kph + or - 5% = 89.25 max. :exclamation:

On the second point, the max speed limit for HGV’s on UK Motorways is 60 mph, so why not. :question:

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we are going through a driver efficencey fad at the moment.i call it a fad because about august time when it gets busy all that goes out the window for the cause of “get the stuff down the road and we don’t care how you doit” :stuck_out_tongue: .

i am being assessed on wednesday so if you see a blue truck doing 40mph all the way from norwich to leicester thats me :blush:

no doubt will be looking for another job next week :wink:

as for my scania it sits nicely in the middle of the green band at 50mph, i was overtaken by nearly every truck on the a449 to newport last week only to see brake lights when they rounded the corner and the safety camera van was in the layby :open_mouth:

and most of them i caught by the cauldra roundabout (spelling)

jon