Kevin wrote:Let me put it another way.
Gareth wrote:Kevin wrote:Let me put it another way.
The problem is you've picked an arbitrary constraint, a fixed cruising speed, and you're willing to adjust everything else to find the most economical way to use that fixed cruising speed. You're even willing to ignore variations in journey time.
The degree to which it is arbitrary is illustrated by your unwillingness to choose a lower cruising speed, which would be even more economical.
I can see that it makes a fun thought experiment but apart from that I see little value. Most people are either aiming to improve economy or to complete the journey within a fixed time.
Kevin wrote:I would think the first example would be the most economic, but I'm not clever enough to do the calculations. Has anyone done the maths and come up with an answer? If they have, please show your workings.
GJD wrote:Kevin wrote:I would think the first example would be the most economic, but I'm not clever enough to do the calculations. Has anyone done the maths and come up with an answer? If they have, please show your workings.
I don't know the answer, but I'd note that for a given length of straight, the quicker you accelerate to your chosen cruising speed, the less distance you will cover in the acceleration phase, so the longer you will be maintaining that speed before it's time to slow down again for the next thing. The quicker you accelerate, the more fuel you will use in your cruise phase simply because it will be longer.
GJD wrote: The quicker you accelerate, the more fuel you will use in your cruise phase simply because it will be longer.
Kevin wrote:GJD wrote: The quicker you accelerate, the more fuel you will use in your cruise phase simply because it will be longer.
And would the converse apply? The slower you accelerate the more fuel you will use in your acceleration phase simply because it will be longer.
Kevin wrote:There must be a trade off between the two
Kevin wrote:but where does that trade off lie?
Kevin wrote:There must be some evidence out there somewhere that has established the facts.
mefoster wrote:This sounds like the hypermiling technique sometimes known as "Pulse and Glide" or "Burn and Coast". Accelerate harder, but for a shorter period of time to reach the same cruise speed.
Kevin wrote:martine wrote:Lets not forget that those preparing for an Advanced Test need to be able to demonstrate safe, good progress. Whether you drive like this all the time is entirely up to you. That said, I don't think any examiner would worry about a candidate approaching a hazard too slowly as long as they get briskly up to the speed limit after the hazard (and if appropriate of course).
I can see repeated hesitation might be an issue but I don't believe that's the OP's main point.
Topper's book Very Advanced Driving has some interesting ideas about making progress, some of which I wouldn't think are really acceptable. One in particular has the 'very advanced driver' apparenly squeezing up the right-hand side of a car waiting at a roundabout and then slotting in behind a car on the roundabout ahead of the car waiting. A bit extreme and I'm not sure, even if I wanted to drive like that, such an opportunity would often present itself. I would say this goes beyond safe, good progress.
GJD wrote:Kevin wrote:There must be some evidence out there somewhere that has established the facts.
Must there be? Couldn't the answer depend on the type of engine (turbodiesel vs NA petrol for example), or be different for different engine models? I've no idea whether variables like that might have an impact, but I see no reason to assume they definitely wouldn't.
fungus wrote: It is many many years since I have picked up my copy of Very Advanced Driving by A Tom Topper, but if IIRC, he recommended signaling right when waiting in busy traffic to turn left, then when some one invites you out, switch the indicator to left and emerge.
Kevin wrote:I see someone has suggested that brisk acceleration is part of a hypermiling technique, which makes me think that someone has worked out whether or not there is some benefit in it. I dunno, just putting it out there to those that might have a better knowledge or greater access to resources than I have.
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