In a climate of ever increasing fuel costs, what are the best ways to extract as many MPG as you can out of your cars?
Is there any truth in better MPG when you drive around with windows shut or never having a full fuel tank?
I know switching off a/c and never driving with a roof rack helps but anyone got any other tips?
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Keeping windows and sunroof shut can make a substantial difference as they add drag which means you need to use more power to overcome this. I don't know the exact figures but it is much more of a issue at high speed than low.
Technically, running around with a full fuel tank means more weight to drag around and therefore slightly worse fuel consumption but I doubt it's significant and you also lose queuing up and stopping / starting at the pump as well as those extra drips from the nozzle.
If you want to go really OTT of course you can strip out all the seats, carpets etc to get the weight down as much as possible...
Accelerating briskly can actually decrease fuel consumption and not changing up too early can make a difference as well as being kinder to the engine.
Probably the most useful tip though is to get a decent pair of shoes or a bike and leave the car at home for any journeys under a mile or so.
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Get someone else to drive :)
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See what your car handbook says. The 205 one gave a list of ways of adding to consumption, and by how much. The 306 says consumption increases 25% between 70 and 80mph (among other things).
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Drive like someone over 80 years old, they typically use £3 of fuel a month.
I maintain the rate of acceleration is the killer, it sure is in my car as the display points out. Many moons ago, I had a BMW that had a thing at the bottom of the rev counter that also showed this, Trouble is, I am one of those that like's a clean get-away!
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On a previous post I gave my views on how I managed to increase my fuel consumption from 42mpg to something like 48 mpg
1. Don't use your car for short journeys as this will drastically reduce your average mpg for the tank.
2. Cut your speed, on my daily journey, I cut it from 75mph on the motorway to 55-60. Left for work 5 mins earlier and still arrived on time.
That is basically as technical as I got and it worked. And, it exercised my legs as well! :)
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... but anyone got any other tips?
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how about this half-baked idea
www.halfbakery.com/idea/2-4_25_20extra_20car_20pow...2
they also have something for the petrol additives brigade (see also supermarket vs branded debate)
www.halfbakery.com/idea/Boiled_20Gasoline_20Engine
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Its very easy, there is a direct relation to how many times, how fast, and how hard you press that lever under your right foot. Moderating your right foot is the only sure way to cut fuel consumption.
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How much you use the other lever under your right foot makes a difference, too (left-foot brakers know what I mean). If you drive to minimise your use of the brakes, you won't have to use the other one so much.
Mind you, I have recently bought a 500cc motorbike that does 65mpg, and only my respect for the rear tyre prevents me from making full use of the performance...
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>How much you use the other lever under your right foot makes a difference, too (left-foot brakers know what I mean). If you drive to minimise your use of the brakes, you won't have to use the other one so much.
Indeed.
RH pedal uses fuel.
Middle pedal wastes it.
Back off 1 second before you would have braked. Every time.
Then do it 2 seconds before.
Lots more backing off = less braking = better MPG.
(plus as big bonus - it's safer)
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Never mind the mpg JBJ, stick it to her in the bends. My Harley does about 130 miles on a 5 gal tank before hitting reserve and I could care less.....
Buy some Metzeler tyres though, life savers they are. TGIF.
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Drive as if you were not certain that the brakes were going to work.
Anticipate, anticipate, anticipate. Ease off in advance of possible slow-ups.
The right-hand pedal is your investment in precious momentum, paid for in expensive petrol. The middle pedal is for throwing it all away unused.
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"Never mind the mpg"
You're quite right, G - it's not why you buy a bike, is it? Still, I thought it was pertinent, as I doubt I could get much less than 60mpg, even if I rode like a lunatic. Also, if everyone rode bikes, think what a shock it would be to Gordon! Still, in view of what you say about Metzelers, perhaps I should be trying harder to wear out the factory-fitted Bridgestones...
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I have a very neat little UK origin article about MPG and that ludicrous PC phrase "powered 2 wheelers" which appeared on my local forum posted by a Filipino pal who lives in UK.
I would like to re-post it here but I need to get the source first to authenticate it, which I am trying to do. It may well be moddy-fied for its content (it mentions JC, no, no, not that one, the one who witters one about motoring, in less than complimentary terms) but it's good enough to try.
OT but the Metzelers are worth the money. No one I ride with would touch anything else. Softer and not so long lasting but you probably aren't doing big mileage anyway. I got a big 160 on my rear (if you take my meaning) which is solid as a rock. Even the thin one I've got in front (stop tittering please, it's a 21", so there) on my street H-D is miles away from the Dunlops I had before.
Enjoy yourself but always use good rubber, (as the Mama-san in my local haunt likes to keep reminding the customers when they select their nightly take-away).
................out.
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"nightly take-away"
For a moment there, I thought you were talking about food!
I'd heard that Bridgestone BT54's were pretty good, but I bow to your superior knowledge of Metzelers. Should I be looking for a particular variety?
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"halfbakery"
Thanks for the link Dalglish. That's going to keep me quiet for ages (stop cheering at the back!)..
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j-b-jagworth
re: halfbakery
yes, isn't the internet a wonderful place?
there are quite a few motoring related items in that half-baked halfbakery site!
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As I've posted in several similar threads over the past 4 months, I've changed my driving style. I mostly stick with the lorries now in lane 1 of the motorway, and I will average about 60mph where the road allows, only pushing it higher when conditions deems so (such as having to move into lane 2 to overtake and other vehicles are behind). I brake less, due to anticipating the road situation well in advance, and have turned it into a bit of a game with myself. Can I time my arrival at the red lights so that I can sail on thru while the numpty who tore past me has to accelerate from standstill.
I've gone from getting about 320 miles from a full tank to achieveing 460 last week. That's almost a 50% increase.
The added benefits are that I feel a lot less stressed, get to enjoy an extra few minutes of an educational prog on radio 4, always seem to catch those in a rush up at the next set of red lights, and don't have to keep an eye out for the fuzz now.
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Agreed on all points pdc. Why is everyone in such a hurry anyway?
Ed.
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Ah, but you don't understand.
Those who indulge in "ragamuffin" driving syle actually think they are normal - and it's us who are "holding them up".
You know - like the "sin of all sins" - doing 30 in a 30 limit.
"Many drivers who are fast, aggresive and inconsiderate are quite happy with the way they drive and do not acceept it is unsafe.
They tend to think that their behaviour is more common than it really is, and that it is the result of external pressures rather than their own choice.
These rationalisations create barriers to attitude change, and need to be challenged to allow scope for change"
Not my words - from Chapter 1 of Roadcraft.
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Can't fault either of you. I'm thoroughly bored with being bullied too. If you're in such an incredible hurry, perhaps you need a different lifestyle, to set off earlier, or to get a job where you're not hassled by suits who believe that money makes you happy and worthwhile.
There's probably room for a motoring version of the "Slow Food" movement - see www.slowfood.com/
I don't mean duffers driving Maestros at 32mph everywhere. I mean a more measured, qualitative take on the driving experience, with a touch more perspective on whether your arrival time is that important...
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"I don't mean duffers driving Maestros at 32mph everywhere"
You should come to the Isle of Wight - it's practically an art form here!
Still, I agree that catching up those in a rush at the next set of red lights is deeply satisfying, and more than adequate compensation for not rushing yourself. One way of honing this technique is to drive a 2CV (or anything similar with no noticeable acceleration) and try to preserve your momentum...
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Agree pdc... I've changed my driving style too after watching Top Gear a few weeks ago believe it or not! JC drove an Audi diesel from London to Edinburgh and back on one tank of diesel. One idea he talked about to max mpg is to accelerate downhill and use momentum to get up the hills.
Since changing driving style my Mazda 626 has done 680 miles from a full tank - 59 mpg. Previously I was getting anything from 520 - 600 miles.
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Since changing driving style my Mazda 626 has done 680 miles from a full tank - 59 mpg. Previously I was getting anything from 520 - 600 miles.
But is it as much fun?
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Yes, but it's a different kind of fun... I've done the performance car fun having owned a turbo Impreza for a couple of years. Now I'm happy to see how smoothly I can drive, how much money I can save to have fun in other ways and how stress free I am after a drive. My wife's also happy that she's not getting thrown around which is what used to happen in the Impreza.
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JC drove an Audi diesel from London to Edinburgh and back on one>> tank of diesel.
As a result of seing that prog I dared to do about an extra 5 miles the other week when the computer was estimating that I could do 0 miles on the fuel left in the tank.
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The more weight being carried the higher the fuel consumption - fuel, for example, equals weight.
Keep the tank only as full as required for use over a few days ahead, but without risking getting to too low a level as this can affect the catalyst.
You obviously appreciate the need to keep windows closed and remove unused racks etc but, on the other hand, if you have a/c you will use additional fuel if it is in operation.
That leads to the possibility of having to decide whether to use the a/c in hot weather and keep all the windows closed or turn it off and open the windows... Hobson's Choice, but I'd turn on the a/c....:-)
Other ways are to ensure that the engine is fully maintained and serviced, don't make unnecessary or short journeys and not to let the engine idle to allow it to "warm up". Driving off immediately and keeping acceleration down until the engine is warm is much kinder.
Taking your hiking boots off would help too by ensuring minimum throttle levels once the car is at the required speed.
A funny aside is that someone queried in the Mail recently whether having English flags on their cars in support of the (failed) Euro 2004 championship bid added to fuel consumption?
The answer was yes - worked out scientifically - and the more flags the higher the (admittedly small) increased consumption.
So every little helps. But winning the National Lottery would be the best solution of all...:-)
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I believe that if you drive at the level of maximum torque output that this cuts the fuel usage.
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Having just moved to a diesel SRi Vectra (2.2), I initially thought that using the air con would seriously reduce my consumption. Whilst cruising on the motorway and watching the fuel consumption in real time, I tried an experiment and turned on the air con, slowly increasing fan speed.
I found that in most cases, for fan speeds 1 and 2 there was barely any change in fuel consumption, but increasing fan to top speed gave a noticeable drop in fuel consumption of about 10% or greater.
Ive read that air con in diesel cars will give a greater reduction in fuel economy than in a petrol car, is this true?
I am using the air con every day on my return journey from work, I do 100 miles a day so 50 with the air con between cardiff and chipping sodbury. I am averaging 58mpg a week and getting about 650 miles or more out of a tank.
Look forward to seeing if it improves in the winter!
I tend to agree though with driving techniques and I cruise at 65mph on the inside lane of the motorway and always gently accelerate and reduce use of brakes when possible.
I have also found that quite often in town, 3rd is more economical than 4th at 30mph, and the computer really is useful in getting to know when to change gear and what revs to maintain. In a diesel its always to easy to drive at very low revs in top, I sometimes cruise at 800rpm in 4th! But! Its not always economical to do so as maybe in a petrol.
Also driving sometimes faster is more economical as when you hit a gradient the car has more momentum to overcome it. On the \"flat\" stretch of M4 just before the severn crossing and after it, I can reach over 75mpg! Often I get 62mpg at 65mph, but the slightest need to accelerate and maintain the speed on a gradient drops this into the 40\'s.
Its fun trying to squeeze the best economy from your car, and it doesnt mean driving super slow. Better still, keeping the car moving means faster overtaking and better, safer driving.
Simon
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Ah it's good to know that people still live in Chipping Sodbury, it used to be like Stoke Poges the butt of jokes for sounding slightly rude or made up. I used to live at Coalpit Heath just down the road which also got some funny comments.
On a serious note though according to many experts running your air con all the time is the way to stop the system developing leaks or de-gassing.
If you balanced the cost of re filling/servicing your aircon versus a saving in fuel costs by not using it then you might be surprised where the balance lay?
Personally both my vehicles (both diesels) have Climate Control so I just tend to st auto and forget about it.
Cheers
SIMON
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I'm not trying to be clever but "Get a decent map and use it" helps some people a lot.
On many an occasion I've found people I know not using the most direct route because "I always go the way I know".
I'm getting a new car soon - it's my first diesel - main reason - economy in France. If diesel vs. petrol figures are to be believed I calculate my French diesel fuel costs will be 50% of my UK petrol ones. That's potentially £hundreds a year.
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As usual, the Slow Acceleration is best brigade are out in force.
The most economical way to drive is to accelerate at your maximum torque revs. This is surprisingly fast, but overall, you will find that you get better MPG in total. You use more while accelerating, but you reach your cruising speed quicker and hence use less overall.
I don't expect to be believed, as we've been fed disinformation (not misinformation) on this for so long.
Here's a scientific view.
www.honestjohn.co.uk/forum/post/index.htm?v=e&t=90...4
V
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>The most economical way to drive is to accelerate at your maximum torque revs. This is surprisingly fast, but overall, you will find that you get better MPG in total. You use more while accelerating, but you reach your cruising speed quicker and hence use less overall.
Depends.
As long as you do "the other half".
Which involves backing off long before others brake.
The very worst MPG drivers are welly - brake hard, welly - brake hard.
Braking - the frequency and forcefulness of - has more effect (adversely of course) on MPG than how many revs you use when accelerating.
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Oh - just to confirm - I am not of the "minimum acceleration" camp.
I advocate using more acceleration than most.
This is an illustration:-
Here is an example of acceleration sense:
Imagine a half-mile straight of clear road leading to a sharp bend.
Many drivers will lightly accelerate over at least two-thirds of the straight, then brake for the bend.
Instead, firmly use full power when the view is best at the beginning of the straight, over, say, one third of the distance. During this time, assess the speed for the bend and gradually ease off the power - so that engine braking brings the speed to exactly that required for the corner.
Fuel consumption is the same for both methods, and acceleration sense assists concentration, alertness and safety.
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Happy with that, except for "Fuel consumption is the same for both methods". The second way will almost certainly use less fuel, as you'll be at a point to feather the throttle (i.e. maintain whatever speed you reach) earlier.
V
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"I always go the way I know"
If you've got a computer (and I suspect you have), it's worth getting a copy of Autoroute, which will give you a raft of alternative ways of getting from here to there, with mileages and a 'most economical' route, based on speed and fuel consumption.
The results are often surprising.
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a copy of Autoroute, which will give you a raft of alternative ways of getting from here to there, with mileages and a 'most economical' route, based on speed and fuel consumption. The results are often surprising.
Indeed they are. Some of the routes it generates are impossible or staggeringly bad. I frequently find it very unreliable in creating often simple routes.
It is very useful for finding house numbers and producing area maps with road names.
On longer trips it is worth previewing alternative routes from the comfort of home prior to departing. If route one fouls up then you should be primed to take route two.
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And once upon a time Autoroute didn't know about restricted access junctions on motorways, so would create an impossible route.
It may have been fixed in the latest 2004 release.
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Not only that, pdc - I have seen an example of Autoroute just ignoring the length of about 4 miles of road it had included in a route. I don't think its calculation was less than the straight line, but it came close.
Also going up an irrelevant side-road, turning round and carrying on where it turned off. Amusing, but not helpful.
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"I've read that air con in diesel cars will give a greater reduction in fuel economy than in a petrol car, is this true?"
Using a/c will drain off some power (bhp) from the engine, just as the fan or the screen-heater will. They can't
tell what sort of engine it is. If it's big, you won't notice the a/c; if it's a 1.5 diesel you almost certainly will. Probably the latest cars have less draining a/c's?
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800RPM in 4th? If I reduce my speed to 800RPM in 4th I get a very unpleasant banging and clattering noise coming from somewhere. Clutch isn't slipping though. Anyone care to hazard a guess?
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Possibly the SUV driver two feet behind whose headlamp flashing you haven't responded to firing a repeater shotgun in the air?
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"...to max mpg is to accelerate downhill and use momentum to get up the hills."
This causes swmbo to observe, consecutively:
'You're going too fast'
. . . .
'Why are we in the slow lane, why don't you overtake'
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Andrew-T seems to be the only one so far who has touched on the unnecessary use of electrical equipment. How many times have I seen vehicles stationary in a queue using headlights, foglights, brake lights, wipers and God knows what else? The energy to drive these devices has to come from somewhere, and that's from the fuel placed in the tank (and not from the battery as many believe).
In answer to his query about the losses created by aircon, I belive it is the case that the more modern systems fitted to cars from about 4 years ago are now more selective with regard to the setting selected by the driver, rather than being simply on or off and nothing in between. Once again, however, the energy comes from the fuel, and running the aircon compressor full-time when it isn't always required will undoubtedly increase consumption.
Having been a life-long practitioner of fuel-saving techniques, it is also the case that there are considerable savings to be had with regard to tyre, clutch and brake wear, as well as the improved margins of safety (as previously mentioned by another). And before you ask - no, I don't drive around at 35 in a 60, but I do raise and lower my speed a little more gradually than some, and I short-shift my 406 HDi so as to remain somewhere near the revs for peak torque.
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>>The energy to drive these devices has to come from somewhere, and that's from the fuel placed in the tank (and not from the battery as many believe).
Tee hee! I had a friend who was convinced that his car used no petrol when stationary at traffic lights. 'Well what's the battery for, then?' he asked.
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>>The energy to drive these devices has to come from somewhere, and that's from the fuel placed in the tank (and not from the battery as many believe).
Obviously this is true in general, but it is not quite the whole story. Some of the fuel energy goes into moving the vehicle, but some is wasted via heat loss or other inefficiencies such as friction. So a device that could reduce these losses might pay for itself in energy terms.
For example, switching on the heater blower might simply be diverting lost energy from the radiator to the car's interior.
A turbo or supercharger presumably consumes less energy than it contributes.
And it may theoretically be possible to design air conditioning that runs on waste heat from the engine, much as some refridgerators run by burning gas.
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A turbo or supercharger presumably consumes less energy than it contributes.
Wow! I want one!
Err.. doesn't the turbo contribute energy by way of more fuel being thrown into the chamber, though? So it doesn't actually put any energy in itself.
And won't it consume some energy by slightly increasing the effort required to expel the exhaust gases?
If anything actually consumes less energy than it contributes then we have the starting point for a perpetual motion machine, the ultimate nightmare of all those who work in the patent system.
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If anything actually consumes less energy than it contributes then we have the starting point for a perpetual motion machine, the ultimate nightmare of all those who work in the patent system.
Hi patently! Don't web forums like this come close to being a perpetual motion machine (of the circular variety)? ;-)
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Nah. We just consume energy and turn it into heat. We don't produce anything useful.
;-)
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I've always thought this website is rather like hot air blower...
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I think you are all missing my point. I wasn't suggesting that you can get something for nothing. I was saying there may be occasions when a machine can use its fuel more efficiently, such as by finding another outlet for the waste (heating the interior instead of the outside air) or by causing it to run at a more efficient speed, or loading, or temperature, or with better gas flow.
All tuners know that extracting more power is not necessarily at the expense of worse fuel economy.
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Fair enough.
I think this applies more to tuning rather than to adding a turbo, though. I'd be surprised if a turbo version of the same car could run with better mpg.
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machine can use its fuel more efficiently, such as by finding another outlet for the waste (heating the interior instead of the outside air)
Isnt that the way the old beetle heater worked? and very smelly it was too
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And the heater in the air-cooled Citroen GS, although that wasn't smelly at all. Mind you, it did complicate the exhaust system somewhat...
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All car heaters work like that, smelly or not. The waste heat from the engine has to be dissipated somewhere. Either through the radiator in the front, or from the heater matrix inside.
Waste heat is an energy resource, and potentially it can be harnessed to do something more useful than heat the atmosphere. It can simply be transferred to where it is needed, or more subtly be used to drive some other process, eg a refridgerator or air conditioning. (I am currently involved in designing a building that will use the sun to power cooling, and photo-electraic cells to power the pumps to circulate the water)
To return to the thread, I am simply saying that a gadget does not necessarily have to be a consumer of additional fuel - it might actually facilitate more efficient use of the fuel.
Take an example. Imagine a water/oil pre-heater that took its power from the battery. As long as the battery had the capacity to stand the initial drain, then it could quite easily be the case that the improved engine efficiency derived from running hot right from start-up would more than compensate for the need to recharge the battery.
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>>Waste heat is an energy resource, and potentially it can be harnessed to do something more useful>>
Cliff Pope has pinpointed a fact of which scientists and engineers are well aware.
My father was an engineer and I always recall, as a child, him telling me that you couldn't destroy something, only turn and/or convert it into something else e.g if you burn something you get heat and ashes.
In similar vein, my late mother-in-law used to collect the offerings from passing riding schools' horses and spread it over the garden to make things grow better, including the vegetables...:-)
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