Speed Awareness Course this PM - What to expect?
Discussion
4040vision said:
NGee said:
Hackney said:
I went on a speed awareness course recently and I was pleasantly surprised ....
When asked for feedback at the end mine was, "everyone should do this course. repeatedly"
I have often wondered why, if this course is so good [and the general consensus of opinion on this thread seems to be that it is], it is used as a punishment. Surely if it's about education and prevention then everyone should be made to do the course, as part of their driving training, before they are allowed to take the driving test.When asked for feedback at the end mine was, "everyone should do this course. repeatedly"
OK, it will only help new drivers but it's a start.
bmw535i said:
rainmakerraw said:
I can travel at the red line and use no fuel at all (think about it...). Higher revs doesn't absolutely mean higher fuel consumption. For a start you're using much less throttle in 3rd than 4th at 30mph, and in urban areas you'll be lifting off much more often in response to traffic and other hazards, resulting in a pulse-and-glide style drive based almost solely around acceleration sense. Contrast that with a 'keep the throttle applied constantly while the car chugs along just above tickover in 4th' style of driving in a higher gear, which often necessitates braking to rein in the car before wasting fuel re-accelerating.
In practice the difference in fuel consumption between the two is pretty negligible, though on long straights the benefits of the higher gear start to outweigh the flexibility of the lower one. With the lower, more flexible gear engaged you tend to accelerate more sharply for the first third of a straight and then coast down (using no fuel) for the final two thirds. This approach also means much more flexibility and safety on approach to developing hazards like traffic, junctions and pedestrians. In a higher gear you're on a steady throttle (and thus burning fuel) for the entire stretch of road, and then braking before doing it all over again. I suspect this is what your 'presenter' was on about. I can only guess however, as *touch wood* I've never been on one of the bloody things.
Not sure if you're being serious?In practice the difference in fuel consumption between the two is pretty negligible, though on long straights the benefits of the higher gear start to outweigh the flexibility of the lower one. With the lower, more flexible gear engaged you tend to accelerate more sharply for the first third of a straight and then coast down (using no fuel) for the final two thirds. This approach also means much more flexibility and safety on approach to developing hazards like traffic, junctions and pedestrians. In a higher gear you're on a steady throttle (and thus burning fuel) for the entire stretch of road, and then braking before doing it all over again. I suspect this is what your 'presenter' was on about. I can only guess however, as *touch wood* I've never been on one of the bloody things.
He might be serious but he's not making any sense. A long time since I read such rubbish.
Countdown said:
Being in a higher gear doesn't automatically mean you're using less fuel. e.g. Labouring the car in 4th/5th when you're pootling around town is going to use more fuel than driving in 3rd.
There may be some cars where that's true but not many. Most modern cars will be more economical in a higher gear, all other things being equal, and most modern cars will be quite happy in 4th at 30mph as long as you're not asking them to accelerate quickly.
This advice is similar to that told to my wife when on one, that it was more economical to to go up to high revs before changing gear than it was to change up early. Patently wrong.
REALIST123 said:
Countdown said:
Being in a higher gear doesn't automatically mean you're using less fuel. e.g. Labouring the car in 4th/5th when you're pootling around town is going to use more fuel than driving in 3rd.
There may be some cars where that's true but not many. Most modern cars will be more economical in a higher gear, all other things being equal, and most modern cars will be quite happy in 4th at 30mph as long as you're not asking them to accelerate quickly.
I can put the car into 5th and let it burble along at a bit above tickover and be doing an indicated 99mpg on a trailing throttle but it's very rare to be in that situation driving around town.
REALIST123 said:
bmw535i said:
rainmakerraw said:
I can travel at the red line and use no fuel at all (think about it...). Higher revs doesn't absolutely mean higher fuel consumption. For a start you're using much less throttle in 3rd than 4th at 30mph, and in urban areas you'll be lifting off much more often in response to traffic and other hazards, resulting in a pulse-and-glide style drive based almost solely around acceleration sense. Contrast that with a 'keep the throttle applied constantly while the car chugs along just above tickover in 4th' style of driving in a higher gear, which often necessitates braking to rein in the car before wasting fuel re-accelerating.
In practice the difference in fuel consumption between the two is pretty negligible, though on long straights the benefits of the higher gear start to outweigh the flexibility of the lower one. With the lower, more flexible gear engaged you tend to accelerate more sharply for the first third of a straight and then coast down (using no fuel) for the final two thirds. This approach also means much more flexibility and safety on approach to developing hazards like traffic, junctions and pedestrians. In a higher gear you're on a steady throttle (and thus burning fuel) for the entire stretch of road, and then braking before doing it all over again. I suspect this is what your 'presenter' was on about. I can only guess however, as *touch wood* I've never been on one of the bloody things.
Not sure if you're being serious?In practice the difference in fuel consumption between the two is pretty negligible, though on long straights the benefits of the higher gear start to outweigh the flexibility of the lower one. With the lower, more flexible gear engaged you tend to accelerate more sharply for the first third of a straight and then coast down (using no fuel) for the final two thirds. This approach also means much more flexibility and safety on approach to developing hazards like traffic, junctions and pedestrians. In a higher gear you're on a steady throttle (and thus burning fuel) for the entire stretch of road, and then braking before doing it all over again. I suspect this is what your 'presenter' was on about. I can only guess however, as *touch wood* I've never been on one of the bloody things.
He might be serious but he's not making any sense. A long time since I read such rubbish.
In the real world around town at 30mph I have yet to find a demonstrable difference on any of my recent cars whether in 3rd or 4th, except that 3rd offers more control and less time on the throttle (with more immediate response when it is needed). For example in my current car (2.0 TSI 220ps DSG), at 30mph in 3rd it's about 1,900rpm and in 4th it's around 1,500rpm. In 3rd gear I'll rarely need throttle and a lightest touch at that. All time off the throttle is time and distance travelled using zero fuel. In 4th, conversely, not only is the response dull but I need a near constant throttle input (and hence constant fuel usage) to maintain speed. I'm not sure why you think that's so ridiculous.
Revs don't equate to fuel usage / MPG, rather load does. Otherwise you'd use precisely twice as much fuel at 1,600rpm (whether up hill or down, on the throttle or off, irrespective of gear or throttle input) as you did simply idling at 800rpm. Clearly that's not the case.
While travelling uphill, a higher gear and more open throttle can be more efficient (due to pumping losses, the same reason acceleration is usually most efficient at almost WOT but with ~2,000rpm upshifts in most cars). It's the reason a DCTs will race to high gears despite the effect on real world driving experience. This info was taken from conclusions drawn from published engineering experiments at MiT, so if you think they're wrong feel free to link an alternative study (or better yet publish a rebuttal in the relevant journals). I'm always willing to learn something new. For regular driving there's not much in it, especially with many of today's eco minded gearboxes. Again, I'd love some actual evidence that I've been taught incorrectly, as I'd happily change my mind. So far, the real world bears out the original statement as true.
Edited by rainmakerraw on Sunday 23 April 20:52
bmw535i said:
Using a lower gear and higher revs uses less fuel? Hmmmmm
I think I'll just ignore that little pearl of wisdom.
What an insightful counter-argument to the engineering information I provided. You've changed my mind completely; I'll let the team at MiT know as soon as they open tomorrow. I think I'll just ignore that little pearl of wisdom.
Again, you're assuming constant throttle input - in which case you'd be correct about the higher gear - but not to worry. There are far more important things in life and I've run out of f
ks to give.rainmakerraw said:
What an insightful counter-argument to the engineering information I provided. You've changed my mind completely; I'll let the team at MiT know as soon as they open tomorrow. Again, you're assuming constant throttle input - in which case you'd be correct about the higher gear - but not to worry. There are far more important things in life and I've run out of fks to give.
I'm not aiming to change your mind or counter argue. Again, you're assuming constant throttle input - in which case you'd be correct about the higher gear - but not to worry. There are far more important things in life and I've run out of fks to give.Chill out mate and use whatever gear you like, it makes no odds to me how much fuel you use or how much you like redlining your car.
bmw535i said:
I'm not aiming to change your mind or counter argue.
Chill out mate and use whatever gear you like, it makes no odds to me how much fuel you use or how much you like redlining your car.
I'm as chilled as you like mate, believe me. Chill out mate and use whatever gear you like, it makes no odds to me how much fuel you use or how much you like redlining your car.
I just can't fathom how so many threads descend into a circle jerk of 'he's talking rubbish' and 'headnods' when there is absolutely no actual evidence, fact or substance in the counter argument. If you think something's wrong, by all means explain why and how. Provide evidence (journal articles, maths and physics always preferred) and substantiate your rubbishing of the other poster's claims. Otherwise, it's probably best not to say the other person is chatting st (especially when you seem to have misunderstood what was said). JMHO and it wasn't aimed at you personally. Have a good evening. 
rainmakerraw said:
bmw535i said:
I'm not aiming to change your mind or counter argue.
Chill out mate and use whatever gear you like, it makes no odds to me how much fuel you use or how much you like redlining your car.
I'm as chilled as you like mate, believe me. Chill out mate and use whatever gear you like, it makes no odds to me how much fuel you use or how much you like redlining your car.
I just can't fathom how so many threads descend into a circle jerk of 'he's talking rubbish' and 'headnods' when there is absolutely no actual evidence, fact or substance in the counter argument. If you think something's wrong, by all means explain why and how. Provide evidence (journal articles, maths and physics always preferred) and substantiate your rubbishing of the other poster's claims. Otherwise, it's probably best not to say the other person is chatting st (especially when you seem to have misunderstood what was said). JMHO and it wasn't aimed at you personally. Have a good evening. Somewhatfoolish said:
I agree that you are describing a far better way of driving and indeed it's the approach I adopt myself, but it simply isn't more economical. If it were, then it would be a recommended technique at higher speeds too for motorway driving etc as the same argument you're making would apply.
On a motorway you tend to be making progress at a fairly constant speed in the same direction for a long period of time. That's the exact scenario in a 30mph limit I suggested 4th would be better for economy in my OP, and its exactly when I'd be telling my Associates to change up also. 
Around hazard rich urban environments you're not on a straight motorway but rather adapting to changes in traffic, changes in direction, cross flow traffic opportunities (if you please ), pedestrians etc all the time. As such it suits 3rd gear driving (for economy) much better as you spend more time off throttle or on a very light throttle setting with the car doing the work (rather than fighting 4th to maintain progress). Try it. I actually just got home from an hour of trying this very thing around the city after the comments a few posts up in the thread. I left the car in manual mode the entire time, always accelerated briskly and left it in 3rd for anything less than a 40 or 50 limit (road depending). I got better MPG than I've had all week lol. Of course every car, engine and gearbox is different (not to mention driver...) but it works well for me and it suits a particular way of driving economically and safely, i.e. to System. Suck it and see...
You just went out for an hour as a result of this thread!! Blimey.
Not sure how you figure you'd use the throttle less in third - surely you need to use more throttle and revs to achieve the same speed in a lower gear?
Also as soon as you lift off the engine braking would be greater than in 4th or 5th.
As you say every car is different, but in both of mine 5th gear is best at 30 for economy and smoothness.
Please don't feel compelled to go out driving for another hour, I thought no fks were given 
Not sure how you figure you'd use the throttle less in third - surely you need to use more throttle and revs to achieve the same speed in a lower gear?
Also as soon as you lift off the engine braking would be greater than in 4th or 5th.
As you say every car is different, but in both of mine 5th gear is best at 30 for economy and smoothness.
Please don't feel compelled to go out driving for another hour, I thought no f
ks were given rainmakerraw said:
Would you like to explain and present evidence as to why, without relying on 'because' or 'I just know'? You use absolutely no fuel at all regardless of revs if your foot is off the throttle.
Because I mapped my engine to do precisely that, as do the OEM's.I can set the rpm point to anything I wish, currently I set it to 2000rpm as the cut off point, so off throttle above 2000rpm my engine uses no fuel.
On a sprint, I disable this, so I get flames out the back on the over run as it ignites in the exhaust/turbo, as that's funny.
The rest of your posts on how engines use fuel is utter garbage, sorry.
rainmakerraw said:
jsf said:
The rest of your posts on how engines use fuel is utter garbage, sorry.
Yet back in the real world economy doesn't suffer and drive improves. Which was my point. As for the hour out, any excuse to clear out the cobwebs (I didn't spend it all at 30mph. ). This is the base fuel map for my engine, you will find the same basic structure on any engine.
Across the top is engine rpm
across the left side is inlet vacuum/boost (1000 is atmospheric pressure)
The value in the table is how long the fuel injector is open
You will see, as the engine rpm climbs, even with the same engine vacuum/boost the amount of fuel injected increases.
jsf said:
You are talking nonsense man.
This is the base fuel map for my engine, you will find the same basic structure on any engine.
Across the top is engine rpm
across the left side is inlet vacuum/boost (1000 is atmospheric pressure)
The value in the table is how long the fuel injector is open
You will see, as the engine rpm climbs, even with the same engine vacuum/boost the amount of fuel injected increases.
Assuming constant throttle though for the entire distance travelled in both gears, right? From a cursory glance, your map shows a difference of about 0.2 milliseconds worth of fuel injected at any particular stage/level of inlet vacuum at the revs under discussion. That's 0.2 milliseconds of extra fuel. How much does 0.2 milliseconds extra fuel spray kill MPG on an average real world urban run? I'll wager not much as I never see any appreciable real world difference and again it would surely rely on constant throttle in both instances. Since third means you can be off the throttle completely, and thus using no fuel, for a lot more of the time for any given A to B section of road, it surely averages out? It's literally the difference between near constant throttle in 4th for the duration, or pulse and glide in a lower gear. As I said I find no real world difference between the two give or take a fraction of a MPG, and it's more drivable and arguably safer real world. So, as with anything you pays your money and takes your choice. This is the base fuel map for my engine, you will find the same basic structure on any engine.
Across the top is engine rpm
across the left side is inlet vacuum/boost (1000 is atmospheric pressure)
The value in the table is how long the fuel injector is open
You will see, as the engine rpm climbs, even with the same engine vacuum/boost the amount of fuel injected increases.
As I said if I've been taught wrong and my real world observations are wrong I'm 100% happy to change my mind. It's how we learn. But so far the assumptions seem to be that both conditions are equal in application, when they're not. At your own admission you use no fuel when you're on the over run on most cars, which is entirely my point. The higher gear requires more constant throttle input and loses those extra revs, leaving you no room for 'play' in being off throttle on approach to a hazard, necessitating a down change anyway. I just don't find it makes any real world difference worth bothering about.
The point at issue is how does the power required compare between maintaining the same speed at in higher rather than a lower gear. Or to put it another way, how does the power loss due to inefficiency vary between the higher revs and the lower. Generally speaking the higher revs will be less efficient due to friction losses, but at very low revs, say below 2000 rpm in a petrol, this may not apply.
So yes, normally higher gear means less fuel consumed. This would certainly apply travelling at motorway speeds in 5th instead of 4th. But at town speeds it isn't [b/necessarily[/b] so.
So yes, normally higher gear means less fuel consumed. This would certainly apply travelling at motorway speeds in 5th instead of 4th. But at town speeds it isn't [b/necessarily[/b] so.
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