mpg experiment
Discussion
Hi,
I read some article in the paper a few weeks ago about hypermiling - some
thing (apparently) started in the USA about people using techniques to get
better mpg out of their vehicles. Typically they use either a Prius or a Honda
Insight and there is one guy who's had over 100mpg out of his insight. But
they claim to be able to get better mileage out of anything, even a crappy US
gas guzzler.
So, I decided to try some of the things in my car (A 1999 Honda Accord 1.8) Namely:-
1) Tyres are all 3psi over inflated, for less rolling resistance.
2) Roll (or coast) up to an stop situation as soon as you know
theres no actual need to acclerate (or keep constant speed) up
to it. Cons: Annoys drivers behind.
3) Coast down any hill that's around, or any downwards semi-slope.
(I can coast about 7% of my average trip home from work)
4) Never drive above 60mph (This one was hard for a whole tankful)
Cons: Really annoys drivers behind, esp if you do the best mpg 50mph
in a 60 zone. But it was a science experiment !!
5) Keep the revs low. I rarely went above 3000 for the test tankful -
which is a shocking waste of a good VTEC.
6) No hard braking or acceleration - basically 2) and 5) combined.
The best I've ever had from this Accord was 34 mpg as I remember, and
the worst was about 25, which comes from driving it around in the vtec
zone all of the time.
The conditions for the entire 408.5 miles of test fuel - a full tank, were
mixed driving. Everything from Motorway to B road. Honda's quoted figure
for mixed driving in the 1999 Accord 1.8 is 33.6 mpg.
And the result of all this? 37.14mpg. So it does work, and I didn't even
try and of the extreme ideas. But it is sooo boring ! Given this distances
I drive, the difference between this and my normal 34mpg driving adds up to
about an extra £15 a month. Perhaps it's worth paying this to enjoy the driving though.
Michael.
I read some article in the paper a few weeks ago about hypermiling - some
thing (apparently) started in the USA about people using techniques to get
better mpg out of their vehicles. Typically they use either a Prius or a Honda
Insight and there is one guy who's had over 100mpg out of his insight. But
they claim to be able to get better mileage out of anything, even a crappy US
gas guzzler.
So, I decided to try some of the things in my car (A 1999 Honda Accord 1.8) Namely:-
1) Tyres are all 3psi over inflated, for less rolling resistance.
2) Roll (or coast) up to an stop situation as soon as you know
theres no actual need to acclerate (or keep constant speed) up
to it. Cons: Annoys drivers behind.
3) Coast down any hill that's around, or any downwards semi-slope.
(I can coast about 7% of my average trip home from work)
4) Never drive above 60mph (This one was hard for a whole tankful)
Cons: Really annoys drivers behind, esp if you do the best mpg 50mph
in a 60 zone. But it was a science experiment !!
5) Keep the revs low. I rarely went above 3000 for the test tankful -
which is a shocking waste of a good VTEC.
6) No hard braking or acceleration - basically 2) and 5) combined.
The best I've ever had from this Accord was 34 mpg as I remember, and
the worst was about 25, which comes from driving it around in the vtec
zone all of the time.
The conditions for the entire 408.5 miles of test fuel - a full tank, were
mixed driving. Everything from Motorway to B road. Honda's quoted figure
for mixed driving in the 1999 Accord 1.8 is 33.6 mpg.
And the result of all this? 37.14mpg. So it does work, and I didn't even
try and of the extreme ideas. But it is sooo boring ! Given this distances
I drive, the difference between this and my normal 34mpg driving adds up to
about an extra £15 a month. Perhaps it's worth paying this to enjoy the driving though.
Michael.
mej023 said:
Hi,
I read some article in the paper a few weeks ago about hypermiling - some
thing (apparently) started in the USA about people using techniques to get
better mpg out of their vehicles. Typically they use either a Prius or a Honda
Insight and there is one guy who's had over 100mpg out of his insight. But
they claim to be able to get better mileage out of anything, even a crappy US
gas guzzler.
So, I decided to try some of the things in my car (A 1999 Honda Accord 1.8) Namely:-
1) Tyres are all 3psi over inflated, for less rolling resistance.
2) Roll (or coast) up to an stop situation as soon as you know
theres no actual need to acclerate (or keep constant speed) up
to it. Cons: Annoys drivers behind.
3) Coast down any hill that's around, or any downwards semi-slope.
(I can coast about 7% of my average trip home from work)
4) Never drive above 60mph (This one was hard for a whole tankful)
Cons: Really annoys drivers behind, esp if you do the best mpg 50mph
in a 60 zone. But it was a science experiment !!
5) Keep the revs low. I rarely went above 3000 for the test tankful -
which is a shocking waste of a good VTEC.
6) No hard braking or acceleration - basically 2) and 5) combined.
The best I've ever had from this Accord was 34 mpg as I remember, and
the worst was about 25, which comes from driving it around in the vtec
zone all of the time.
The conditions for the entire 408.5 miles of test fuel - a full tank, were
mixed driving. Everything from Motorway to B road. Honda's quoted figure
for mixed driving in the 1999 Accord 1.8 is 33.6 mpg.
And the result of all this? 37.14mpg. So it does work, and I didn't even
try and of the extreme ideas. But it is sooo boring ! Given this distances
I drive, the difference between this and my normal 34mpg driving adds up to
about an extra £15 a month. Perhaps it's worth paying this to enjoy the driving though.
Michael.
What works for basically an electric car at low speed will not normally do so for a standard petrol engine car:-I read some article in the paper a few weeks ago about hypermiling - some
thing (apparently) started in the USA about people using techniques to get
better mpg out of their vehicles. Typically they use either a Prius or a Honda
Insight and there is one guy who's had over 100mpg out of his insight. But
they claim to be able to get better mileage out of anything, even a crappy US
gas guzzler.
So, I decided to try some of the things in my car (A 1999 Honda Accord 1.8) Namely:-
1) Tyres are all 3psi over inflated, for less rolling resistance.
2) Roll (or coast) up to an stop situation as soon as you know
theres no actual need to acclerate (or keep constant speed) up
to it. Cons: Annoys drivers behind.
3) Coast down any hill that's around, or any downwards semi-slope.
(I can coast about 7% of my average trip home from work)
4) Never drive above 60mph (This one was hard for a whole tankful)
Cons: Really annoys drivers behind, esp if you do the best mpg 50mph
in a 60 zone. But it was a science experiment !!
5) Keep the revs low. I rarely went above 3000 for the test tankful -
which is a shocking waste of a good VTEC.
6) No hard braking or acceleration - basically 2) and 5) combined.
The best I've ever had from this Accord was 34 mpg as I remember, and
the worst was about 25, which comes from driving it around in the vtec
zone all of the time.
The conditions for the entire 408.5 miles of test fuel - a full tank, were
mixed driving. Everything from Motorway to B road. Honda's quoted figure
for mixed driving in the 1999 Accord 1.8 is 33.6 mpg.
And the result of all this? 37.14mpg. So it does work, and I didn't even
try and of the extreme ideas. But it is sooo boring ! Given this distances
I drive, the difference between this and my normal 34mpg driving adds up to
about an extra £15 a month. Perhaps it's worth paying this to enjoy the driving though.
Michael.
Keeping revs low as possible is not such a good idea. You need to be within certain ranges of revs, depending on engine design, to maximise it's efficiency and engine life. There are many drivers who trundle round at 35/40 in the false belief that they are getting best economy whereas slightly higher speeds would yield better results.
Another fact is that on even minor up gradients, an engine reving freely (but not excessively)in a lower gear on a light throttle opening will usually give better economy than low revs in higher gears especially at slower speeds - (as much as 40/50% with carburretor induction but dont expect such a gain with modern fuel injection) . Again this comes down to A/D, right gear for the speed and conditions. Many cars have a built in computer so it is easy to monitor real time consumption to which gear/speed combination gives best mpg. The trick to economy is keeping a light load on a free reving engine in it's torque band as opposed to power band.
Surely, no hard braking or acclerating is just good AD practice ! Excepting overtakes, flow and pace is what it is all about. If you get it right, about the only time you need to brake is to stop. Again I have seen research that shows, that say in a 30, building up speed fairly rapidly in a low gear and then dropping straight into the highest gear the car can accomodate, can be just as econimical as a slow build up through the gears. It also avoids upsetting the guy behind.
As pointed out, coasting wastes fuel as you are feeding an engine with idle mixture. If no fuel is called for by the injection system on overrun, none is delivered. Far better to anticapate that engine braking will bring you almost to a stand if you need to stop and to stay in gear on long down gradients.
Raising tyre pressures is a complete false economy. It may marginally reduce rolling resistance but not only are you reducing the grip on the road you will also wear the centre of the tread out prematurely. Thats a whole load of pounds you will be spending on new rubber. Worse still, if the car is subject to examination by the police your name could change to 'Defendant !' DON'T DO IT.
Looking at your results you only got about a 10% improvement which if i am honest is not much of a reward for all your efforts. I think it is fair to say that most drivers who under go A/D training find they gain better fuel comsumption as an additional benefit to their improved driving technique. More significantly, many find they make better progress as well. I don't exactly hang about but I usually better the manufactures quoted figures with ease.
One undisputable fact in the Ameriacn article is that keeping your speed around 50 - 60 is more economic than cruising at higher speeds. That may be boring but think of all that extra dosh you have to enjoy self !
Edited by Jules2477 on Friday 11th July 23:28
Whilst I find it difficult to believe, there was an article in a motoring periodical (sorry can`t remember which) that suggested that with modern computer controlled engines the use of full throttle in each gear to the required speed obtained the most frugal mpg.
There was a group of drivers who tried the technique and all reported improved MPG.
Certainly not a technique I`d want to employ.
There was a group of drivers who tried the technique and all reported improved MPG.
Certainly not a technique I`d want to employ.
crisisjez said:
Whilst I find it difficult to believe, there was an article in a motoring periodical (sorry can`t remember which) that suggested that with modern computer controlled engines the use of full throttle in each gear to the required speed obtained the most frugal mpg.
There was a group of drivers who tried the technique and all reported improved MPG.
Certainly not a technique I`d want to employ.
There was a group of drivers who tried the technique and all reported improved MPG.
Certainly not a technique I`d want to employ.
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Edited by Jules2477 on Friday 11th July 23:32
Inny said:
Isn't coasting dangerous? Or is coasting not what I understand it to mean: letting the car roll along in neutral?
- *************************************************************************************************************************************
For those of us old enough to remember, cars like ponderous old Auntie Rover's, some models had a freewheel built in to save fuel. Thus the car coasted when engine power was not called for. Quite obviously if you are driving the car at speed, especially on a twisty road, where the combination of power, gear , speed is important to balance and control, coasting is a no no. By contrast straight{ish) road and no particular demands on the cars handling, perhaps quite low speeds, it could be perfectly safe.
TrevorH said:
Coasting doesn't work in modern cars. Their fuelling systems are set so that they deliver zero fuel when the engine is on the overrun (crrect term?), whereas a coasting engine will still be using fuel to maintain its idle.
Over-run makes the fuel delivery stop and save you tons of fuel. My average mpg climbs by 1 or 2 mpg over a 500 mile tank when I do this down a 1.2 mile stretch of road on the way to work. went to sister's 40th recently, was with the parents who took the scenic route (long) to gran's old house, went on the motorway as was hungover, but legal to drive afaik and drove at 55 mph so that did not get there too early
was reading 85 mpg in diesel ford focus, usually it is only 50-55 mpg
was reading 85 mpg in diesel ford focus, usually it is only 50-55 mpg
What I've learned:
1. Coasting is ok,and saves petrol...
There is no law against coasting nor anything specifically dangerous providing you still have full control of the vehicle. However, the word 'Control' is the important bit as the police can prosecute if it can be shown that a driver did not have proper control over the vehicle.
[/quote]
2. Being hungover saves petrol too....
[quote=Scraggles]hungover, but legal to drive afaik...reading 85 mpg in diesel ford focus, usually it is only 50-55 mpg
[/quote]
1. Coasting is ok,and saves petrol...
There is no law against coasting nor anything specifically dangerous providing you still have full control of the vehicle. However, the word 'Control' is the important bit as the police can prosecute if it can be shown that a driver did not have proper control over the vehicle.
[/quote]
2. Being hungover saves petrol too....
[quote=Scraggles]hungover, but legal to drive afaik...reading 85 mpg in diesel ford focus, usually it is only 50-55 mpg
[/quote]
I agree with everything said so far. I'd like to add though that coasting definitely isn't safe practise, even on a straight road, as mentioned above. If you need to take avoiding action, such as swerving round a deer or child etc, you'll have much better control of your car with some power on. The problem isn't in the initial swerve, but when straightening up, whereupon keeping the power on will stabilise the car. Swerving without any drive is a scary experience!
I should also say that backing off in good time to come to a halt is generally good practise. It saves on brakes and fuel, as well as gently slowing the traffic behind so no one is caught napping!
I should also say that backing off in good time to come to a halt is generally good practise. It saves on brakes and fuel, as well as gently slowing the traffic behind so no one is caught napping!
TrevorH said:
Coasting doesn't work in modern cars. Their fuelling systems are set so that they deliver zero fuel when the engine is on the overrun (crrect term?), whereas a coasting engine will still be using fuel to maintain its idle.
True, but engine braking wastes a lot more energy than using some fuel to maintain an idle speed. So which is more efficient depends on how much you want to slow down. If you don't want to slow down, coasting in neutral with the engine idling is more efficient than just taking your foot off the accelerator.Cheers,
FT.
Just an observation, but there seems to be a common thought on the Advanced Driving forum that the unexpected won't occur on the road. I'm not trying to stir things, but it just interests me, because this "coasting isn't dangerous" notion is about the second or third time in the last month people have thought that because they're following IAM practise with regard to their observation the unexpected (diesel spills, deer, children etc) won't occur. curious..
The implication on this particular thread from a few people is that if you are on a straight road and you can see what's ahead, then coasting is ok, even though I'm sure we all agree that it's dangerous because you can't swerve or change direction with stability and safety.
What if a deer runs out in front of you and there's no time to brake so you need to swerve?
Forgive me if I've got the wrong idea about what some people are saying, but it's a worrying thought that the unexpected isn't accounted for. After all, it's the unexpected that causes accidents.
The implication on this particular thread from a few people is that if you are on a straight road and you can see what's ahead, then coasting is ok, even though I'm sure we all agree that it's dangerous because you can't swerve or change direction with stability and safety.
What if a deer runs out in front of you and there's no time to brake so you need to swerve?
Forgive me if I've got the wrong idea about what some people are saying, but it's a worrying thought that the unexpected isn't accounted for. After all, it's the unexpected that causes accidents.
Fume troll said:
True, but engine braking wastes a lot more energy than using some fuel to maintain an idle speed. So which is more efficient depends on how much you want to slow down. If you don't want to slow down, coasting in neutral with the engine idling is more efficient than just taking your foot off the accelerator.
Could you explain that to me, please? I can't see how using no fuel could be less efficient than using some fuel...?.
The implication on this particular thread from a few people is that if you are on a straight road and you can see what's ahead, then coasting is ok, even though I'm sure we all agree that it's dangerous because you can't swerve or change direction with stability and safety.
What if a deer runs out in front of you and there's no time to brake so you need to swerve?
The whole concept of swerving for an animal is usually the most dangerous thing you can do. Just ask your self how many people have been seriously hurt or killed by leaving the road, having a head on or worse still, colliding with an overtaking vehicle in these circumstances? If you dont have time to do a mirror check and react, it is far far safer to brace your self and your passengers for the invitable direct hit.
The implication on this particular thread from a few people is that if you are on a straight road and you can see what's ahead, then coasting is ok, even though I'm sure we all agree that it's dangerous because you can't swerve or change direction with stability and safety.
What if a deer runs out in front of you and there's no time to brake so you need to swerve?
- ***************************************************************************************************************************************
The whole concept of swerving for an animal is usually the most dangerous thing you can do. Just ask your self how many people have been seriously hurt or killed by leaving the road, having a head on or worse still, colliding with an overtaking vehicle in these circumstances? If you dont have time to do a mirror check and react, it is far far safer to brace your self and your passengers for the invitable direct hit.
Edited by Jules2477 on Monday 14th July 18:52
Jules2477 said:
.
The implication on this particular thread from a few people is that if you are on a straight road and you can see what's ahead, then coasting is ok, even though I'm sure we all agree that it's dangerous because you can't swerve or change direction with stability and safety.
What if a deer runs out in front of you and there's no time to brake so you need to swerve?
The whole concept of swerving for an animal is usually the most dangerous thing you can do. Just ask your self how many people have been seriously hurt or killed by leaving the road, having a head on or worse still, colliding with an overtaking vehicle in these circumstances? If you dont have time to do a mirror check and react, it is far far safer to brace your self and your passengers for the invitable direct hit.
Where I'm coming from is the number of threads recently on this forum that seem to completely disregard the chance of an emergency happening. I was on a thread recently where I was advocating keeping the car balanced in a corner just in case you hit oil or a damp patch of road, and I got comprehensively battered out of the thread for suggesting such a thing, because apparently it doesn't matter how you drive dynamically if you're driving at road speeds?! Idiotic and ill-thought out, but it was the majority viewpoint. Again we had it last year with a heel and toe thread, where I was saying it's best to keep your right foot on the brake at all times, stay in the right gear at all times, and also keep the driven wheels as far away from the limit at all times by rev matching. Stay controlled, stay safe basically. There was unanimous disaproval of that as well, with people saying that it's better to come to a halt declutched, or move your right foot off the brake to rev match etc etc.The implication on this particular thread from a few people is that if you are on a straight road and you can see what's ahead, then coasting is ok, even though I'm sure we all agree that it's dangerous because you can't swerve or change direction with stability and safety.
What if a deer runs out in front of you and there's no time to brake so you need to swerve?
- ***************************************************************************************************************************************
The whole concept of swerving for an animal is usually the most dangerous thing you can do. Just ask your self how many people have been seriously hurt or killed by leaving the road, having a head on or worse still, colliding with an overtaking vehicle in these circumstances? If you dont have time to do a mirror check and react, it is far far safer to brace your self and your passengers for the invitable direct hit.
Yes, swerving is always a last resort, but I can assure you if you're driving a Caterham and you're faced with a deer at head height, it's a good plan! I had that situation a few months after buying my first Caterham and that controlled smooth avoiding action probably saved my life. I was doing 60mph at about midnight on a B road and a deer jumped right out in front of me, within maybe 30 yards. After you've made the initial "swerve" (or direction change), the car will be a lot more stable if you're on the power than if you're off it. There are a few reasons for that, but the main one is that the momentum might cause oversteer, and power will pull you out of that and get the weight transfer onto the back wheels. Most tankslappers are caused by people backing off and throwing the weight of their cars forwards off the rear wheels. Anyway, we might not be talking about a full on swerve, it's always dynamically better to have your right foot connected to the engine if you want to control a car properly. If you don't believe me, then go out and go round a corner with the car in neutral; you'll scare the willies out of yourself!
RobM77 said:
Jules2477 said:
.
The implication on this particular thread from a few people is that if you are on a straight road and you can see what's ahead, then coasting is ok, even though I'm sure we all agree that it's dangerous because you can't swerve or change direction with stability and safety.
What if a deer runs out in front of you and there's no time to brake so you need to swerve?
The whole concept of swerving for an animal is usually the most dangerous thing you can do. Just ask your self how many people have been seriously hurt or killed by leaving the road, having a head on or worse still, colliding with an overtaking vehicle in these circumstances? If you dont have time to do a mirror check and react, it is far far safer to brace your self and your passengers for the invitable direct hit.
Where I'm coming from is the number of threads recently on this forum that seem to completely disregard the chance of an emergency happening. I was on a thread recently where I was advocating keeping the car balanced in a corner just in case you hit oil or a damp patch of road, and I got comprehensively battered out of the thread for suggesting such a thing, because apparently it doesn't matter how you drive dynamically if you're driving at road speeds?! Idiotic and ill-thought out, but it was the majority viewpoint. Again we had it last year with a heel and toe thread, where I was saying it's best to keep your right foot on the brake at all times, stay in the right gear at all times, and also keep the driven wheels as far away from the limit at all times by rev matching. Stay controlled, stay safe basically. There was unanimous disaproval of that as well, with people saying that it's better to come to a halt declutched, or move your right foot off the brake to rev match etc etc.The implication on this particular thread from a few people is that if you are on a straight road and you can see what's ahead, then coasting is ok, even though I'm sure we all agree that it's dangerous because you can't swerve or change direction with stability and safety.
What if a deer runs out in front of you and there's no time to brake so you need to swerve?
- ***************************************************************************************************************************************
The whole concept of swerving for an animal is usually the most dangerous thing you can do. Just ask your self how many people have been seriously hurt or killed by leaving the road, having a head on or worse still, colliding with an overtaking vehicle in these circumstances? If you dont have time to do a mirror check and react, it is far far safer to brace your self and your passengers for the invitable direct hit.
Yes, swerving is always a last resort, but I can assure you if you're driving a Caterham and you're faced with a deer at head height, it's a good plan! I had that situation a few months after buying my first Caterham and that controlled smooth avoiding action probably saved my life. I was doing 60mph at about midnight on a B road and a deer jumped right out in front of me, within maybe 30 yards. After you've made the initial "swerve" (or direction change), the car will be a lot more stable if you're on the power than if you're off it. There are a few reasons for that, but the main one is that the momentum might cause oversteer, and power will pull you out of that and get the weight transfer onto the back wheels. Most tankslappers are caused by people backing off and throwing the weight of their cars forwards off the rear wheels. Anyway, we might not be talking about a full on swerve, it's always dynamically better to have your right foot connected to the engine if you want to control a car properly. If you don't believe me, then go out and go round a corner with the car in neutral; you'll scare the willies out of yourself!
Anyway back to thread, good technique, without coasting, in normal driving conditions is best practice for all round economy. - MPG, and wear and tear.
Edited by Jules2477 on Monday 14th July 20:05
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