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How To Reduce Fuel Consumption When Driving And Towing


lottie
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The AA run courses designed to help drivers reduce fuel consumption by up to 15% http://www. aadrivete. ..ses_110323. html

 

 

It gives the following suggestions which it claims should reduce consumption by around 5%:

  • If your vehicle doesn’t have ‘Stop/Start’ technology, deploy your own version. By looking well ahead in traffic or at lights you should be able to judge if you’re going to be stopped for more than 30 seconds. If you are, switch off. Modern starters, batteries and charging systems are quite able to cope with this regime once they are at running temperature.
  • Find out where the engine’s ‘sweet spot’ is (usually the point at which peak torque is being produced) and change up at that point. When overtaking, select a gear that enables you to use that ‘sweet spot’ to best (and most efficient) advantage.
  • ‘Block change’ up the gearbox (1st, 3rd, 6th) when circumstances allow, back off the throttle as much as you can to use the vehicle’s existing momentum to carry it forward, only use the brakes to slow down and don’t exceed the speed limit.

Are these applicable when towing? Any better ideas?

Edited by lottie
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I turn the engine off when in a big static traffic jam or at a level crossing for a tram or train.

 

Not forgetting the filling station.

 

I think cruise control used properly has benefits as well.

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I found I could always beat the mpg that the cruise control got. Mainly because I would lift off slightly going uphill and regain the speed when going downhill. (watching the downhill speed when towing, of course).

 

Beware turning the engine off on a modern turbodiesel if you've just been towing at speed or uphill. Very easy to starve the oilflow to the turbo.

 

I agree absolutely about driving to the maximum torque of the engine - that's generally the most efficient engine speed.

 

I'd love to see some research about whether the alutech caravans, with their more vertical fronts, give lower mpg figures than those which are more streamlined. I suspect the answer is very complicated, and depends upon the towing vehicle - airflow is very complicated!

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Think of Whales and Submarines. They have very rounded fronts but they have no problems.

 

Some say the roofbox on cars is fitted back to front!

Ford C-Max and Coachman Festival 380/2 SE 2006    Motto  Carpe Diem

Still trying to find the perfect pitch. ..110 amp Battery+ 65 watt roof mounted Solar and 25 watt Wind Turbine. LED lighting. Status Aerial 315. Loose chattels marked with UV,. Safefill Gas Fitted.

 

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I would say the 'block change' method is not applicable to towing.

 

Once your outfit is moving particularly on a flat road or a road with a slight downwards incline block changing ie:2nd to 4th or 3rd to 5th is not a problem IME. But now I find driving an auto is more relaxing. :)

 

Regards.

 

Col

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Think of Whales and Submarines. They have very rounded fronts but they have no problems.

If only it were that simple! The car and caravan are sufficiently far apart that the modelling is incredibly complicated. The caravan is running in the turbulence directly behind the car. Indeed, it may well be that the more aerodynamic the car, the worse the effect caused by towing.

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Most people seem to drive in a way to use up the most fuel they can. Approaching a 30 limit they drive at full speed up to it and then slam on the brakes. They floor it when pulling away anywhere.

 

My appraoch is "smooth and calm" and I drive with economy in mind. That I think does more than any one particular habit.

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Building on what Ellisfield says, you can also save money by driving 4 or more seconds from the car in front. I regularly see drivers having to slow down & speed up again when someone in front of them does something, where if they were just a little further back they could simply ease off slightly and let the gap close a bit without needing to take more drastic action. Smooth and calm is usually the most fuel efficient

Edited by A11
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I recently changed caravans from a 1333kg senator to a 1565kg Valencia.

 

When i first got the Valencia i towed it at 55 to 60mph same as the Senator, i was a bit put out to only get 24/26 mpg.

 

With the senator i would return near 30mpg.

 

As an experiment i towed the Valencia at 50 to 55mph, only touching 60 occasionally down hill, this immediately brought the mpg back up to 28/29mpg.

 

So my advise for fuel saving is reduce speed.

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stop / start is great, if you don't want to use the A/C or keep switching the radio on manually each time you stop, Audi had this on one of the first Passats many moons ago, and they dumped it. Wonder why.

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I was told some years ago to save fuel drive as if there are eggs on top of the pedals ( presumably a manual ) and you mustn't break them :huh:

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I recently changed caravans from a 1333kg senator to a 1565kg Valencia.

 

When i first got the Valencia i towed it at 55 to 60mph same as the Senator, i was a bit put out to only get 24/26 mpg.

 

With the senator i would return near 30mpg.

 

As an experiment i towed the Valencia at 50 to 55mph, only touching 60 occasionally down hill, this immediately brought the mpg back up to 28/29mpg.

 

So my advise for fuel saving is reduce speed.

 

 

Reducing speed can save fuel especially when towing a large object like a caravan. Air resistance or drag increases with speed - every time you double your speed the air resistance increases fourfold. This is particularly noticeable as you approach 60mph.

 

But your reduction in mpg follows an increase of weight rather than drag - or do you think your new combination of car and van is less aerodynamic?

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stop / start is great, if you don't want to use the A/C or keep switching the radio on manually each time you stop, Audi had this on one of the first Passats many moons ago, and they dumped it. Wonder why.

 

My (Volvo) radio stays on when the engine is turned off - only turns off when the key is removed.

 

I believe the new generation stop/start is quite sophisticated. ...it doesn't just turn the engine off. It stops it just before top dead centre so it fires almost immediately it begins turning again. I don't think it uses the starter motor to start it either. It uses a reversible alternator.

 

Here is the peugot citroen system

 

http://www. psa-peugeot-citroen. com/modules/stop-and-start/anglais/parent. html

Edited by lottie
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Reducing speed can save fuel especially when towing a large object like a caravan. Air resistance or drag increases with speed - every time you double your speed the air resistance increases fourfold. This is particularly noticeable as you approach 60mph.

 

But your reduction in mpg follows an increase of weight rather than drag - or do you think your new combination of car and van is less aerodynamic?

 

Have you looked at the upright front on the Unicorns, not sweeped back as of old, plus the front of the Unicorn is 4" wider, and the caravan length is over two foot longer, and as you say its heavier.

 

 

My (Volvo) radio stays on when the engine is turned off - only turns off when the key is removed.

 

I believe the new generation stop/start is quite sophisticated. ...it doesn't just turn the engine off. It stops it just before top dead centre so it fires almost immediately it begins turning again. I don't think it uses the starter motor to start it either. It uses a reversible alternator.

 

Here is the peugot citroen system

 

http://www. psa-peuge. ..ais/parent. html

Not used a stop start car, but my son in law works for Merc, so gets a new car every few months, he hates the stop start, it starts quick but theres still a irritating delay to setting off.

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I found I could always beat the mpg that the cruise control got. Mainly because I would lift off slightly going uphill and regain the speed when going downhill. (watching the downhill speed when towing, of course).

 

Beware turning the engine off on a modern turbodiesel if you've just been towing at speed or uphill. Very easy to starve the oilflow to the turbo.

 

I agree absolutely about driving to the maximum torque of the engine - that's generally the most efficient engine speed.

 

I'd love to see some research about whether the alutech caravans, with their more vertical fronts, give lower mpg figures than those which are more streamlined. I suspect the answer is very complicated, and depends upon the towing vehicle - airflow is very complicated!

 

quite happy with 30 -35 mpg towing ours .

i agree with the cruise control thing as well, rarely use it when towing, prefer to not thrash the balls off it at 55mph going uphill when 45-50 in a lower gear suffices.

alot of it is down to reading the road, its amazing what mpg figures are attainable at 5. 30am on a sunday on the run to work when its quiet, slowing down well before junctions and avoiding braking altogether . reset the mpg computer just last sunday and had an average of 61. 2 after the 12. 5 mile commute.

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Beware when you are towing. 50 - 55 MPH will realy anger the lorry drivers. They are able to keep a constant 56MPH. If you interupt them they have a tendancy to cut you up.

 

Best advise is to keep an appropriate speed to the traffic.

 

How many times have you been in a 50 MPH speed limit and you religiously keep to this. But the LGV's always want to overtake you. It's because they are limited to 56MPH and they work better at this speed. They have much less work to do at this speed. Reduce to 50 MPH and they have to keep changing gear.

 

Stay with the flow and you will have a much more comfortable drive.

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Beware when you are towing. 50 - 55 MPH will realy anger the lorry drivers. They are able to keep a constant 56MPH. If you interupt them they have a tendancy to cut you up.

 

Best advise is to keep an appropriate speed to the traffic.

 

How many times have you been in a 50 MPH speed limit and you religiously keep to this. But the LGV's always want to overtake you. It's because they are limited to 56MPH and they work better at this speed. They have much less work to do at this speed. Reduce to 50 MPH and they have to keep changing gear.

 

Stay with the flow and you will have a much more comfortable drive.

 

This is not my experience, driving at 50 to 55mph I find that lorry drivers are most helpful and not in the slightest inclined to cut me up.

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Beware when you are towing. 50 - 55 MPH will realy anger the lorry drivers. They are able to keep a constant 56MPH. If you interupt them they have a tendancy to cut you up.

 

Best advise is to keep an appropriate speed to the traffic.

 

How many times have you been in a 50 MPH speed limit and you religiously keep to this. But the LGV's always want to overtake you. It's because they are limited to 56MPH and they work better at this speed. They have much less work to do at this speed. Reduce to 50 MPH and they have to keep changing gear.

 

Stay with the flow and you will have a much more comfortable drive.

I can see the lorries approaching with the rear view camera, so i'm ready for when they need to pass.

 

When they start to past i lift off completely, that gets them pass very quickly, and i think the driver appreciates that.

 

Obviously common sense has to be used in dense traffic, thats the down side to towing at 55mph, lorries passing.

 

But not all lorries are in a rush, on my last tour, i had a lorry in front for most of the A1 part of the trip, managed to keep a good gap between, so i can't see why any lorry driver should be put out.

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Have you looked at the upright front on the Unicorns, not sweeped back as of old, plus the front of the Unicorn is 4" wider, and the caravan length is over two foot longer, and as you say its heavier.

 

 

Not used a stop start car, but my son in law works for Merc, so gets a new car every few months, he hates the stop start, it starts quick but theres still a irritating delay to setting off.

I've just collected a new E Class last week and it has the 'Eco' stop start system which is a little different to say the least. It can be switched off but I'm leaving it on as I think it must be some good seeing as most of my driving is urban. Had a long motorway drive of 400 miles at the weekend and the car did 46mpg - which at about 80mph most of the time is very good. Can't wait for it to loosen up. I'm towing this week over much the same route and looking forward to checking out the figures for that

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The turbo on my diesel comes in at 2000 rpm

I try to cruise below this figure in 5th gear.

Tyre pressures are important check them

regularly. Injector cleaning additive once a year

helps. and at high cruising speeds, a good polish

job (it added 3mph to the Supermarine Spitfire)

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Our 2011 Lunar has a much more sloping front than our previous Bailey 2008 series 7 Pageant. I have proved that over 3400 miles with each caravan towed by same car the Lunar gives 10% better fuel economy.

Tests carried out over 4 trips on same route each time.

I can only put it down to the more sloping front of the Lunar because the Pageant was quite an upright front. I can see that all the new Baileys have a very upright front.

By the way weights laden of each caravan were almost identical too.

Lunar Ultima 560 towed by VW Tiguan 2. 0TDi

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Guest Benzowner

The turbo on my diesel comes in at 2000 rpm

I try to cruise below this figure in 5th gear.

Tyre pressures are important check them

regularly. Injector cleaning additive once a year

helps. and at high cruising speeds, a good polish

job (it added 3mph to the Supermarine Spitfire)

At 2000 rpm is where the maximum torque is produced on most diesels, I would suggest your turbo is operating well before then, and certainly on my B Class, 1700 rpm in top is 70mph.

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Our 2011 Lunar has a much more sloping front than our previous Bailey 2008 series 7 Pageant. I have proved that over 3400 miles with each caravan towed by same car the Lunar gives 10% better fuel economy.

Tests carried out over 4 trips on same route each time.

I can only put it down to the more sloping front of the Lunar because the Pageant was quite an upright front. I can see that all the new Baileys have a very upright front.

By the way weights laden of each caravan were almost identical too.

 

 

Thanks Darrell. This and what xtrailman says in post #10 is very interesting. There does seem to be a tendency for new vans to become even more brick like and yet there is very little discussion of their aerodynamic drag attributes.

 

Are caravan makers out of line or missing a trick on this? With the AA reporting this week that motor fuel sales are 15% down on last year as people drive less because of the high prices - and comments elsewhere on CT that caravanners are reducing their mileage for the same reason - perhaps they should be paying more attention to the airflow characteristics of vans.

 

Or do caravan manufacturers have other priorities? Maybe they think (or even know) that while its husbands that tend to choose the car, wives have a much bigger input into the choice of the van and that what matters most are its internal attributes rather than its aerodynamics? Reading the "Why did you choose that van. .." thread they don't seem to be entirely wrong.

Edited by lottie
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