PPRuNe Forums

PPRuNe Forums (https://www.pprune.org/)
-   Jet Blast (https://www.pprune.org/jet-blast-16/)
-   -   Saving fuel in a car by not using brakes (https://www.pprune.org/jet-blast/448931-saving-fuel-car-not-using-brakes.html)

stumpey 16th Apr 2011 13:45

Nice one "Cacophonix". That woke the wife up being played at full volume! :D

"Star Rider Instructor", bah late comers jumping on the band waggon. I was an RAC/ACU instructor years before that organisation came about. :ouch:

The throttle works both ways, (Good film as well). The throttle should be used for slowing down. The brakes are for stopping or loosing speed in an emergency!
.
.
But then that was years ago........:}

(And bends are the FUN part of driving. I've even turned round, gone back, and tried that series again just because I knew I could take them better):eek:

Ancient Observer 16th Apr 2011 13:54

...........er, does anyone else think that this is the most boring thread, ever, or is it just me??

wings folded 16th Apr 2011 14:13


...........er, does anyone else think that this is the most boring thread, ever, or is it just me??
Did my best at post 3, but failed evidently.

Parapunter 16th Apr 2011 14:18

Yeah, I weighed in, but got a shoeing off the poindexters round the ear'oles with their spreadsheets.

Cacophonix 16th Apr 2011 14:36


Did my best at post 3, but failed evidently.
You out drolled me in 3 Wings.

Sad to say, though, as soon as one gets into these conversations the more interesting they tend to become and, hey presto, we had Bill Swallow coming at us with narry a brake on and then I was really enjoying the thread thanks to Stumpey:ok:

Bravo73 16th Apr 2011 15:21

I've only scan-read this thread but what the OP needs to read is this:

Hypermiler | Hypermiling Techniques, forum and news

MadsDad 16th Apr 2011 15:40

Early number SAABs (90s?) also had a 'freewheel' mechanism (disconnected the drive when power not applied). I also remember it meant they couldn't be bump-started (as cannot automatics I believe. At least unless you can push them at 30 mph or so).

green granite 16th Apr 2011 15:57

to save trawling through the site go straight to:

Hypermiling Techniques | Hypermiler

Loose rivets 16th Apr 2011 16:02

The original poster is convinced it is irrelevant how one dissipates the stored energy--the saving will come from the average speed during a given sector.

I'm of the opinion, all deceleration will produce heat eventually, except perhaps, the alteration of the world's rotational speed . . . but even then:confused:


Pushing modern autos won't help much, cos the old 30mph thing was when autoboxes had front pumps as well. This could provide the operational pressure to get the mechanisms working.


Bikes:

Another mate has had a succession of superbikes of late. He informed me he doesn't use the back brake. I was astonished, but I stopped riding about the time the first Suzuki Rs came out, so things might have changed. But I doubt it.

This really is thread drift, because most of my time on bikes was spent trying to imitate a photon.

Krystal n chips 16th Apr 2011 17:04

Green granite....

Erm, about that wonderful link you posted...the author seems to have missed a rather salient paragraph or two...entitled :

"How your Granny likes her eggs cooked"...:rolleyes:

Still, in these austere times, nothing like, erm, reinventing the wheel..to coin a phrase.......sorry !:p

green granite 16th Apr 2011 17:37

Judging by some of the remarks on here there are one or two who need to be trained to cook eggs I'm afraid Krystal n chips

wings folded 16th Apr 2011 18:01

Ahhh.

Cooking eggs indeed....

Con-Pilot and I had a half decent thread going on that topic. It sort of sputtered to an end as all threads will.

But Con knows how to cook an egg, and so do I, I think.

mike-wsm 16th Apr 2011 18:54

There was the man in a British sports car who pursued a Bugatti on a white-knuckle drive through the winding roads of the Welsh mountains. On arriving at their destination he mentioned to the Bugatti driver that his brake lights weren't working. "Oh yes they are" said the Bugatti driver putting his foot on the brake pedal and lighting the lights. He hadn't touched the brakes, just used the gearbox with great skill. Necessarily too, Bugatti brakes were never up to much.

Ancient Observer 16th Apr 2011 18:59

This thread collects the prize as the most boring ever.

However, when it comes to brakes that just do not work, my Lotus Elan should get the prize before Bugattis.

Capetonian 16th Apr 2011 19:24


There was the man in a British sports car who pursued a Bugatti on a white-knuckle drive through the winding roads of the Welsh mountains
This reminds me of the cretin in a 4.5 litre diesel Merc who pursued me half way across Switzerland (from Zurich to Montreux) on the motorways - I thought he just happened to be headed the same way - to tell me I was driving too fast. I was driving a 1.6 litre rented Ford Laser or similar and had been doing a steady 135 or so. When I pulled in to refuel, he parked his car over at the side, away from the pumps, and started ranting and raving at me in Schwyzerdeutsch for 'zu schnell zu fahren'. As his rant progressed it became clear that he had simply done this out of his civic duty to inform me I'd been driving too fast, he wasn't even headed my way. He was quite unconcerned by the fact that he'd totally wasted umpteen litres of diesel just to follow me!

Just to wind him up, I asked him in my best High German if he by any chance could speak German! It's a great way to wind up the Swiss (whom I actually quite like but some of them are total dickheads)

gingernut 16th Apr 2011 19:45

My Mrs, has got one of these cars that works out the average MPG. Her ginger fuelled gusto results in all the bad habits previously discussed-jabbing the accelerator, not predicting the road ahead, using the brakes too often etc.

As a "learning tool" I reset the mpg thingy, and let her drive the first leg to Cornwall. The average mpg was, 33. I then made a big song and a dance about resetting the mpg thingy, and showing her how it "should" be done. Smooth acceleration, predicting the road ahead, judicous use of the brakes.

Result? 31mpg:bored:

Couldn't we use some sort of dynamo device to slow us, using the resultant energy produced for something useful, like charging the battery or watching "Debbie does Dallas" on the in car DVD.

G-CPTN 16th Apr 2011 19:55


Originally Posted by Capetonian
When I pulled in to refuel, he parked his car over at the side, away from the pumps, and started ranting and raving at me in Schwyzerdeutsch for 'zu schnell zu fahren'. As his rant progressed it became clear that he had simply done this out of his civic duty to inform me I'd been driving too fast, he wasn't even headed my way.

Apart from the accent, that could well have been the husband of my cousin.

He was a Beamter with vague connections to the Polizei. He carried a handheld 'HALT - POLIZEI' sign in his car and would wave it out of the window at any motorist that he considered 'offended' him.

It was his duty . . .


gingernut, ani fule kno it is downhill to Cornwall and therefore uphill on the way back.

MG23 16th Apr 2011 22:21

Won't the money you save on fuel have to go on overhauling the brakes when they start sticking due to lack of use?

Howard Hughes 16th Apr 2011 23:48

Interesting thread, tends to correlate with what I have discovered in my 10 hours of commuting each week over the past 5 years. I get my worst fuel consumption figures on Saturdays, when every man/woman and their proverbial dog seem to be out on the roads, it would seem on Saturdays that it is very important to not drive at the speed limit and jump on the brakes at random intervals...:rolleyes:

ChrisVJ 17th Apr 2011 00:31

I would think that if the present preoccupation with saving gas continues it is very likely we will see energy reservoirs in road cars before long. In Formula 1 the KERS systems have already shown it is very possible. They are good enough that, while it is only a very small portion of the energy put out by a Formula 1 car, they are limited by rule to 80hp.

That they would work to mitigate the energy required from the engine is obvious. If you slowed a car from, say 70mph to stop and put the energy into a reservoir and then accelerated to say 60mph before that energy was expended, (allowing for losses) you would only need to use the engine from 60mph back to 70mph and then a little power to maintain cruise. All the gas usually used from zero to 60mph would be saved.

Interesting as you would be doing with kinetic/potential/kinetic energy the opposite of what a zooming plane does with potential/kinetic/potential energy.

In the OP's question, given other things are equal, the gas saved is that not used by removing the foot from the accelerator in cruise a little earlier, not hugely significant but it does exist. Less energy put into the system saves the energy taken out by heating the brakes. (As the energy states of the car in the two examples, cruise and stopped, have to the same!)


All times are GMT. The time now is 05:08.


Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.