Drive for fun, for free!
Discussion
Fuel economy.
I know, I know - Pistonheads is a site for motoring enthusiasts who like to drive high performance cars fast, which isn't in any way compatible with economic driving. A few years ago, a friend of mine bought a large, high performance saloon, powered by a very substantial V8 engine. Someone asked him "what about fuel economy?" And he gave the best answer I've yet heard to such a pointless question.
"Well, when it looks like the fuel is getting low, I just stop and put some more in."
We all know that fuel economy has nothing to do with enthusiastic driving, but how much of your driving is actually enthusiastic? By which I mean, how much of your driving is carried out on nice roads, in light traffic in circumstances which allow you to really stretch your cars legs?
I have a daily commute of 23 miles which takes in about a quarter of the M60 at peak hours, and so I reckon that only about 5% of my own driving is enjoyable these days. Add to that the fact that fuel is very expensive and despite some minor fluctuations, its unlikely to ever be considered cheap again and the benefits of an economic driving style become clear.
My thinking is this. If I drive economically when the traffic is heavy and there is little or no opportunity to make progress or drive enthusiastically, then when the traffic is light and the road is nice, I can afford to stretch my car as much as I like and use up the fuel I've saved during the boring driving. In other words, my "fun" driving - when the opportunity arises - doesn't actually cost me anything. As the thread title suggests, when I drive for fun, it's free!
Of course, there are some people, like my friend with the V8, who are lucky enough to not have to worry about the cost of fuel, but even if you are one of those people, what if you're out on a run and you misjudge things and find yourself low on fuel and miles from the nearest garage? In these circumstances, an economic driving style could make the difference between continuing your journey or making that embarassing phone call.
The first thing you should note is that I'm talking about a driving style and not about differemt types of vehicles. There are cars which are promoted on the basis of being very fuel efficient and there are a number of tips floating around the internet on how to ensure your car will use as little fuel as possible - high tyre pressures and weight reduction are two examples I can think of off the top of my head - but this thread is about how to get maximum MPG (or gas mileage if you're a Yankee Doodle) when driving any car, irrespective of whether it's a hyper-efficient supermini or a V12 supercar. The techinques are the same for any car, and the benefits (in percentage MPG terms) can be very similar for any car.
The other thing to remember is that economic driving on the road is like any other style of road driving - a compromise. In much the same way that you cannot safely drive a car to the limit of its performance on the road, it wouldn't be appropriate, most of the time, to drive a car to the limit of its fuel economy capability. You wouldn't, for instance, want to crawl along a motorway slip road with minimal acceleration and then attempt to join a fast-moving lane 1.
Its this difference between real-world driving and unrealistic test conditions which results in the often large differences between manufacturers claimed fuel economy figures and the MPG figures which are realistically attainable in everyday driving. I'll be examining a slightly more practical economic driving style which doesn't assume that you want to take all day to complete your journey.
So lets start with the basics. Firstly, remember that you're trying to achieve maximum miles per gallon. In other words, the distance travelled is just as important as the driving style, so there is no real need to crawl everywhere at a snails-pace.
Secondly, the activities which use up most of your fuel are accelerating and driving uphill. Now, obviously, those activities cannot be avoided in day-to-day driving, but if you think ahead and plan your pogress, you can easily improve your fuel economy.
Thirdly, air resistance is a problem, but again, it's an element of basic physics which you cannot avoid. Driving into a headwind can have a very dramatic effect on fuel economy and even without a headwind, when you're driving At higher speeds (70mph+), most of your fuel is being used to overcome the resistance of the air. If I'm driving in miser mode, I tend to stay within the posted speed limits.
The fourth and final principle to remember is that when travelling downhill, in gear, with your foot completely off the throttle, a car is using virtually no fuel whatsoever. Many reports (and my own car manual) state that a car is using no fuel at all when coasting in gear, but I find that difficult to accept - although I'm happy to be corrected by someone more knowledgable. Whatever the truth on this question, coasting in gear (as opposed to coasting in neutral or with the clutch depressed - which allows the engine to drop to idle revs, which does require the use of some fuel) is the most fuel-efficient state to be travelling in and effectively gives you "free" mileage.
So, how do we string all these principles together into an economic driving style? Lets look at acceleration first - this is the real killer when it comes to fuel economy, so the less acceleration you have to carry out, the better.
Momentum is king when it comes to MPG, so a good advanced driver is already at an advantage in this regard. If you can plan ahead to avoid having to slow unecessarily for hazards, get an early view at a roundabout so you can join it without having to come to a stop, and maintain reasonable speed through a series of bends using acceleration sense rather than having to brake and then accelerate again - all principles of good, advanced driving - then you're on your way to developing an economic driving style.
If, however, you stop at every hazard and roundabout before accelerating away, and use a "clog and anchor" style, using heavy braking and accelerating through corners, then you're likely to use much more fuel than is necessary.
Of course, some acceleration is necessary, and I find that using no more than the first quarter of the throttle pedal's travel is generally enough to make reasonable progress in most circumstances. Try to combine the quarter pedal technique with maximum revs of 2000rpm before changing up a gear and (in most cars at least) you'll be using as little fuel as possible.
Be flexible though - as mentioned previously, if you're joining a motorway, take a flexible gear and use as many revs as you need to match the speed of vehicles in lane 1, but once you've reached your desired speed, there is no need to go through every gear sequentially - just pop it into top gear, relax your pressure on the accelerator and sit at your desired speed with as little pressure on the pedal as required to maintain your speed.
I mentioned up-hills earlier and these require a little planning. Try to maintain, or even gain a little speed on the approach to an uphill stratch, and then aim to reach the top with as little throttle as possible. I'm not a big fan of losing speed for no apparant reason, but gradully losing a little speed on an uphill incline is usually fine and most other drivers generally do it without even realising.
A smooth driving style is a big advantage when you're in miser mode. If you're smooth and gentle - not just with the accelerator, but with the brakes also - then your MPG will improve. Treat the pedals as though there's an egg underneath them.
Many cars these days are fitted with stop-start systems. These systems recognise when the car is stationary and in neutral, and then switch off the engine whilst the car remains stationary. Dipping the clutch to take first gear causes the engine to re-start almost instantly and you're ready to go.
When I first tried a couple of cars with this system, I hated it - it felt very unnatural and I turned it off. I'm now on my second car with stop-start fitted and I leave it on all the time. I got used to it and I simply cannot argue with the fact that an idling, stationary car is using fuel when it really doesn't need to. I was originally concerned about battery life, but I've never had a problem in 30-odd thousand miles, so I'm now a proponent of stop-start systems.
Maintaining a constant speed once you're up and running is important. If your speed is inconsistant, it invariably will involve a constant pattern of unecessary deceleration, followed by unecessary acceleration - the MPG killer. So once you're up to your chosen speed, keep a regular check on your speedo and try to keep your speed constant.
And the final point I mentioned - coasting in gear - is the biggest fuel-saver of all. On any downhill gradient whatsoever, you should aim to reduce your throttle presssure to zero. Take your foot completely off the pedal if it helps. If you want to maintain or increase your speed, leave the car in a higher gear which will minimise engine braking. Alternatively, if you want the car to hold you or reduce your speed a little, take a lower gear - the revs may rise, but fuel use is still (virtually) zero, so don't worry about the raised engine speed.
This all may sound, to some of you, like very basic stuff. I've only scratched the surface to be homest and there are some far more extreme fuel saving methods discussed elsewhere on the internet, but I think this will do as a basic introduction.
And don't forget to use all that fuel that you save by going on a good blast every now and again!
I know, I know - Pistonheads is a site for motoring enthusiasts who like to drive high performance cars fast, which isn't in any way compatible with economic driving. A few years ago, a friend of mine bought a large, high performance saloon, powered by a very substantial V8 engine. Someone asked him "what about fuel economy?" And he gave the best answer I've yet heard to such a pointless question.
"Well, when it looks like the fuel is getting low, I just stop and put some more in."
We all know that fuel economy has nothing to do with enthusiastic driving, but how much of your driving is actually enthusiastic? By which I mean, how much of your driving is carried out on nice roads, in light traffic in circumstances which allow you to really stretch your cars legs?
I have a daily commute of 23 miles which takes in about a quarter of the M60 at peak hours, and so I reckon that only about 5% of my own driving is enjoyable these days. Add to that the fact that fuel is very expensive and despite some minor fluctuations, its unlikely to ever be considered cheap again and the benefits of an economic driving style become clear.
My thinking is this. If I drive economically when the traffic is heavy and there is little or no opportunity to make progress or drive enthusiastically, then when the traffic is light and the road is nice, I can afford to stretch my car as much as I like and use up the fuel I've saved during the boring driving. In other words, my "fun" driving - when the opportunity arises - doesn't actually cost me anything. As the thread title suggests, when I drive for fun, it's free!
Of course, there are some people, like my friend with the V8, who are lucky enough to not have to worry about the cost of fuel, but even if you are one of those people, what if you're out on a run and you misjudge things and find yourself low on fuel and miles from the nearest garage? In these circumstances, an economic driving style could make the difference between continuing your journey or making that embarassing phone call.
The first thing you should note is that I'm talking about a driving style and not about differemt types of vehicles. There are cars which are promoted on the basis of being very fuel efficient and there are a number of tips floating around the internet on how to ensure your car will use as little fuel as possible - high tyre pressures and weight reduction are two examples I can think of off the top of my head - but this thread is about how to get maximum MPG (or gas mileage if you're a Yankee Doodle) when driving any car, irrespective of whether it's a hyper-efficient supermini or a V12 supercar. The techinques are the same for any car, and the benefits (in percentage MPG terms) can be very similar for any car.
The other thing to remember is that economic driving on the road is like any other style of road driving - a compromise. In much the same way that you cannot safely drive a car to the limit of its performance on the road, it wouldn't be appropriate, most of the time, to drive a car to the limit of its fuel economy capability. You wouldn't, for instance, want to crawl along a motorway slip road with minimal acceleration and then attempt to join a fast-moving lane 1.
Its this difference between real-world driving and unrealistic test conditions which results in the often large differences between manufacturers claimed fuel economy figures and the MPG figures which are realistically attainable in everyday driving. I'll be examining a slightly more practical economic driving style which doesn't assume that you want to take all day to complete your journey.
So lets start with the basics. Firstly, remember that you're trying to achieve maximum miles per gallon. In other words, the distance travelled is just as important as the driving style, so there is no real need to crawl everywhere at a snails-pace.
Secondly, the activities which use up most of your fuel are accelerating and driving uphill. Now, obviously, those activities cannot be avoided in day-to-day driving, but if you think ahead and plan your pogress, you can easily improve your fuel economy.
Thirdly, air resistance is a problem, but again, it's an element of basic physics which you cannot avoid. Driving into a headwind can have a very dramatic effect on fuel economy and even without a headwind, when you're driving At higher speeds (70mph+), most of your fuel is being used to overcome the resistance of the air. If I'm driving in miser mode, I tend to stay within the posted speed limits.
The fourth and final principle to remember is that when travelling downhill, in gear, with your foot completely off the throttle, a car is using virtually no fuel whatsoever. Many reports (and my own car manual) state that a car is using no fuel at all when coasting in gear, but I find that difficult to accept - although I'm happy to be corrected by someone more knowledgable. Whatever the truth on this question, coasting in gear (as opposed to coasting in neutral or with the clutch depressed - which allows the engine to drop to idle revs, which does require the use of some fuel) is the most fuel-efficient state to be travelling in and effectively gives you "free" mileage.
So, how do we string all these principles together into an economic driving style? Lets look at acceleration first - this is the real killer when it comes to fuel economy, so the less acceleration you have to carry out, the better.
Momentum is king when it comes to MPG, so a good advanced driver is already at an advantage in this regard. If you can plan ahead to avoid having to slow unecessarily for hazards, get an early view at a roundabout so you can join it without having to come to a stop, and maintain reasonable speed through a series of bends using acceleration sense rather than having to brake and then accelerate again - all principles of good, advanced driving - then you're on your way to developing an economic driving style.
If, however, you stop at every hazard and roundabout before accelerating away, and use a "clog and anchor" style, using heavy braking and accelerating through corners, then you're likely to use much more fuel than is necessary.
Of course, some acceleration is necessary, and I find that using no more than the first quarter of the throttle pedal's travel is generally enough to make reasonable progress in most circumstances. Try to combine the quarter pedal technique with maximum revs of 2000rpm before changing up a gear and (in most cars at least) you'll be using as little fuel as possible.
Be flexible though - as mentioned previously, if you're joining a motorway, take a flexible gear and use as many revs as you need to match the speed of vehicles in lane 1, but once you've reached your desired speed, there is no need to go through every gear sequentially - just pop it into top gear, relax your pressure on the accelerator and sit at your desired speed with as little pressure on the pedal as required to maintain your speed.
I mentioned up-hills earlier and these require a little planning. Try to maintain, or even gain a little speed on the approach to an uphill stratch, and then aim to reach the top with as little throttle as possible. I'm not a big fan of losing speed for no apparant reason, but gradully losing a little speed on an uphill incline is usually fine and most other drivers generally do it without even realising.
A smooth driving style is a big advantage when you're in miser mode. If you're smooth and gentle - not just with the accelerator, but with the brakes also - then your MPG will improve. Treat the pedals as though there's an egg underneath them.
Many cars these days are fitted with stop-start systems. These systems recognise when the car is stationary and in neutral, and then switch off the engine whilst the car remains stationary. Dipping the clutch to take first gear causes the engine to re-start almost instantly and you're ready to go.
When I first tried a couple of cars with this system, I hated it - it felt very unnatural and I turned it off. I'm now on my second car with stop-start fitted and I leave it on all the time. I got used to it and I simply cannot argue with the fact that an idling, stationary car is using fuel when it really doesn't need to. I was originally concerned about battery life, but I've never had a problem in 30-odd thousand miles, so I'm now a proponent of stop-start systems.
Maintaining a constant speed once you're up and running is important. If your speed is inconsistant, it invariably will involve a constant pattern of unecessary deceleration, followed by unecessary acceleration - the MPG killer. So once you're up to your chosen speed, keep a regular check on your speedo and try to keep your speed constant.
And the final point I mentioned - coasting in gear - is the biggest fuel-saver of all. On any downhill gradient whatsoever, you should aim to reduce your throttle presssure to zero. Take your foot completely off the pedal if it helps. If you want to maintain or increase your speed, leave the car in a higher gear which will minimise engine braking. Alternatively, if you want the car to hold you or reduce your speed a little, take a lower gear - the revs may rise, but fuel use is still (virtually) zero, so don't worry about the raised engine speed.
This all may sound, to some of you, like very basic stuff. I've only scratched the surface to be homest and there are some far more extreme fuel saving methods discussed elsewhere on the internet, but I think this will do as a basic introduction.
And don't forget to use all that fuel that you save by going on a good blast every now and again!
Its always the same with these posts - I leave it a couple of days and then think of more observations I could have included. Here are a couple I've subsequently remembered:
With reference to coasting in gear v coasting in neutral, having carried out a little more internet research, it would appear that most modern engines do not use any fuel when coasting in gear, so any progress you can make in gear with a closed throttle would, indeed, constitute "free" miles.
The bit I failed to mention, however, is that coasting should always be carried out in gear anyway - irrespective of whether you're in miser mode or not. Coasting in neutral or with the clutch depressed is bad practice and removes an element of control from the driver. It is occasionally necessary to use some acceleration to avoid an emerging hazard, and coasting in neutral introduces an unecessary delay which isn't present when you're coasting in gear.
I understand that some automatic and DSG gearboxes do allow some neutral coasting, but these systems instantly re-engage drive if the throttle is applied.
The other point I missed was one mentioned by another poster - eco pro and other switchable "eco", "sport" etc. systems.
These systems allow the driver to switch between different throttle maps to suit their intended driving style. Most cars these days employ "fly by wire" throttles, which means that the accelerator pedal is no loger directly connected to the throttle mechanism by way of a cable. Instead, the pedal effectively sends an electronic signal to an actuator, which then operates the throttle.
This means that manufacturers can tune the throttle to respond in different ways. I have a new BMW, which has three settings - a default "comfort" setting, a "sport" setting and an "eco pro" setting.
The default comfort setting gives a straightforward, linear feeling throttle, by which I mean that the engine's output seems to be directly proportionate to the amount of pressure applied to the accelerator. Pretty much identical to how a more traditional, cable-operated accelerator feels.
The sport setting effectively "shortens" the virtual accelerator cable and makes the engine - in it's lower rev range at least - feel much more responsive. I'm not sure if any other electric trickery is employed in this mode, but the impression to me is that the throttle mechanism is "geared up", and the accelerator pedal requires much less of a "prod" to get the car moving.
The third setting - eco pro - seems to do exactly the opposite to the sport setting. It seems to "lengthen" the virtual throttle cable, and in order to get the car to accelerate at anything approaching a brisk pace, it requires a very hefty shove on the accelerator pedal. The idea is that the car is doing what you should be doing and softening your inputs on the accelerator pedal to maximise fuel efficiency. The car manual also states that the air-con runs in a more fuel efficient way, heated mirrors are slower to work etc.
To the mechanically uneducated - Mrs Local for example - the car "feels" faster in sport and slower in eco pro. This isn't the case in reality, as all the cars performance is always available all the time, whatever mode you are in, it just requires different degrees of accelerator pressure to extract it.
If I'm on the daily grind, I tend to use eco pro to help with fuel economy, but the jury is out on how effective it is. I reckon I can match my fuel economy in all three modes, but I've not had the car long enough (or been anal enough yet) to try.
Incidentally, my daughter thinks "comfort" mode is ridiculous, because ther isn't an "uncomfortable" mode.
With reference to coasting in gear v coasting in neutral, having carried out a little more internet research, it would appear that most modern engines do not use any fuel when coasting in gear, so any progress you can make in gear with a closed throttle would, indeed, constitute "free" miles.
The bit I failed to mention, however, is that coasting should always be carried out in gear anyway - irrespective of whether you're in miser mode or not. Coasting in neutral or with the clutch depressed is bad practice and removes an element of control from the driver. It is occasionally necessary to use some acceleration to avoid an emerging hazard, and coasting in neutral introduces an unecessary delay which isn't present when you're coasting in gear.
I understand that some automatic and DSG gearboxes do allow some neutral coasting, but these systems instantly re-engage drive if the throttle is applied.
The other point I missed was one mentioned by another poster - eco pro and other switchable "eco", "sport" etc. systems.
These systems allow the driver to switch between different throttle maps to suit their intended driving style. Most cars these days employ "fly by wire" throttles, which means that the accelerator pedal is no loger directly connected to the throttle mechanism by way of a cable. Instead, the pedal effectively sends an electronic signal to an actuator, which then operates the throttle.
This means that manufacturers can tune the throttle to respond in different ways. I have a new BMW, which has three settings - a default "comfort" setting, a "sport" setting and an "eco pro" setting.
The default comfort setting gives a straightforward, linear feeling throttle, by which I mean that the engine's output seems to be directly proportionate to the amount of pressure applied to the accelerator. Pretty much identical to how a more traditional, cable-operated accelerator feels.
The sport setting effectively "shortens" the virtual accelerator cable and makes the engine - in it's lower rev range at least - feel much more responsive. I'm not sure if any other electric trickery is employed in this mode, but the impression to me is that the throttle mechanism is "geared up", and the accelerator pedal requires much less of a "prod" to get the car moving.
The third setting - eco pro - seems to do exactly the opposite to the sport setting. It seems to "lengthen" the virtual throttle cable, and in order to get the car to accelerate at anything approaching a brisk pace, it requires a very hefty shove on the accelerator pedal. The idea is that the car is doing what you should be doing and softening your inputs on the accelerator pedal to maximise fuel efficiency. The car manual also states that the air-con runs in a more fuel efficient way, heated mirrors are slower to work etc.
To the mechanically uneducated - Mrs Local for example - the car "feels" faster in sport and slower in eco pro. This isn't the case in reality, as all the cars performance is always available all the time, whatever mode you are in, it just requires different degrees of accelerator pressure to extract it.
If I'm on the daily grind, I tend to use eco pro to help with fuel economy, but the jury is out on how effective it is. I reckon I can match my fuel economy in all three modes, but I've not had the car long enough (or been anal enough yet) to try.
Incidentally, my daughter thinks "comfort" mode is ridiculous, because ther isn't an "uncomfortable" mode.
egor110 said:
any tips for smooth driving with a automatic, we have to brake more because we have no engine braking.
Automatics tend to have less engine braking, but the effect is still there, it just requires better forward observations and planning to avoid unecessary braking.I thing spending some time in an automatic is a very good excersise to improve your acceleration sense, anticipation and throttle timing.
Have a read of Acceleration Nonsense and Braking Bad for some tips on how to improve your acceleration sense, reduce your unecessary braking and improve your braking when its necessary.
Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff