Slowing down really does save you money. I tried it.

Yeh, but was it booooring.
Apparently the wind resistance increases as the square of the speed so 120 kph produces 4 times that of driving at 60 and the power required is 8 times.

Does anyone know if their is a linear realationship (rough) between fuel consumed and reduction in speed i. e if you reduce your speed by 10% fr. 100 to 90, is there a reduction in consumption of 10%. If there was I could formulate a mantra to embrace the idea and keep reciting it as I drove along (booringly)

Wigger
Newton told us that E=MVsquared
E= Energy. M= Mass. V= Velocity. Eric.

Eric,

and............ (for dummies)

Wigger.
Energy= fuel. Mass is the weight of the vehicle. Velocity is the speed you drive at. Eric.

Prof Eric,
can't picture what the graph looks like. Is it linear or exponential curve. You need to talk us dummies through it

Ford Ranger 2.5 diesel, Isint that what the Wiggles Use to get around Melbourne?

Dunno,
but there's four of them and they couldn't all get in the front and I don't think you're allowed to stick them in the back. Ranger 2.5's are for sad bast###s.

Wigger.
Sorry I did not make clear.
E= MxV squared.
The energy used is linear with mass, that is double the load and you double the fuel, but the velocity or speed is a square law, that is double the speed and you use 4 times the fuel, and halve the speed and use 1/4 fuel.
This is not absolutely true in a car because the efficiency of the transmission can vary with speed, if you had lots of gears like a road ranger it would be true,
The rule is very close though and will hold if the motor is doing the same revs.
Transmission efficiency is, that is converting fuel into forward motion varies hugely between vehicles, German vehicles in general are about double the efficiency of others. Eric

Prof E E,
Thanks, that's a good explanation and it seems that you are saying that the line(or curve)is roughly linear or straight line.
With this bit of info it seems I can make meaningful decisions
about choosing a speed.
Don't get the last bit though. I thought petrol engines had an efficiency factor of about 15% as a general guide so how can you say that "german" engines have double this. The ranger has a european MRZ diesel and probably achieves its low fuel consumption through the use of variable geometry turbos and very high pressure injection , rather than being the byproduct of a tuetonic prestige engineering.
"the efficiency of the transmission can vary with speed" - are you saying that the ideal is for the cogs to be turning at low speeds.

Wigger.
Efficiency is not just about engines, it includes rolling resistance and aerodynamics. The Europeans have always had expensive fuel so they have evolved there vehicles in that environment. I sometimes drive a tow truck and use a winch to load vehicles, the load on the winch is a very good indicator of rolling resistance, some cars cause the winch to realy struggle whereas Volvo's or Mercs of the same weight are easy on the winch. Eric.

not sure about the mv squared bit.

the speed squared law applies to resistance to the movement of any object through air or water.
the graph concerns aircraft obv, so you can ignore the 'lift induced drag'.
i suppose just the profile drag applies to vehicles.
this would explain the increased energy(fuel) required to push a vehicle past its best drag speed to 30 kph more.


as for mantra's, i set the cruise control for 90 kph, grit my teeth and try not to touch the loud pedal.
meanwhile softly repeating the words of the great prophet," i know i can, i'm sure i can, i know i can, i'm sure i can"

Tks Howie,
Was just about to go down to the tatoo shop and get this diagram done on my forehead so that I could then swivel the rear view mirror and see it as I drove along . Then just in time I realised that it would be back the front and I would only be able to drive at about 30kph in order to focus on it and realy suss it out.
The mantra will be great though.

"Eric Experience posted:
Wigger
Newton told us that E=MVsquared
E= Energy. M= Mass. V= Velocity. "

This describes the energy that a moving body has. All this energy is recovered when you slow down. It tells you nothing about how much energy is needed to keep it moving against wind and frictional losses.

Ah, yes . The old inverse relationship between speed and concentration. I think I'm at my best in terms of concentration
when I'm doing a white knuckled 160 down the freeway.

So, on the premise of your theory, the faster we drive, the safer we will be ...what a load of cr@p!

Absolutely,
grand prix drivers have proved it Crank up the speed each year but the crash rate goes down.

You put yourself in the same category as the most elite drivers on the planet ... give me a break!

Also, correct me if I'm wrong, but ever since they banned 'ground effects' the F1 cars have been restricted almost every year.
If they hadn't been slowed, there wouldn't be track on Earth that could handle them.

Well seems I lost that one

score : S 1 W 0

Shaker posted:
“So, on the premise of your theory, the faster we drive, the safer we will be ...what a load of cr@p!”

You may be laughing, but up until certain degree going faster equals safer. For long trips like from Melbourne to Gold Coast (have done 5, all of them in one day) I personally do not get tired of driving, but rather my eyes and brain get tired from continuous concentration. Therefore if I travel faster, I will spend less time on the road, that translates to being less time nuisance to others and to less time of hard concentrating. As result it is SAFER in my strongest opinion. Certainly “top safe speed” vary greatly because road condition, whether, car condition and driver him(her)self. When we been in NT some years back with no speed limits it is appears like most comfortable speed to drive is about 150-160 km/hr. More then that does not seem that safe and concentration need to be increased dramatically. Proof of my theory is simple – lots of German autobans has no speed restriction and I do not recall any news about their high accident level. And NT (wile being speed limits free) never been on first pages in our news about incredibly high fatality. “Speed kills” slogan invented by stupid TAC, if it would be true there will be no alive pilots by now.

Cheers
Serg

Serg, correct me if I am wrong, but isn't here a huge difference in the road quality between an Autobahn & an Australian country 'highway' ?

Also the NT isn't exactly over populated!

You also showed a distinct shortage of grey matter in comparing the speed of planes with road vehicles.

What worries me the most though, is that you may have a driver's license!

Shaker,

I do have driver license and *LOVE* fast driving. Furthermore - I have it for more then 25 years and never managed put vehicle out of control in whole my life. In fact I never even been involve in an accident. Your points are valid about NT population and about quality of German autobans versus out rural road. But tell me – do you believe that 110 is adequate speed limit on excellent stretches of Hume highway? I do not think so. BTW from curiosity I managed 210 km/hr when been in NT (actually was trying to make more then speedo shows (220), but it started getting too unstable to push envelop any future and I give up), and I would not consider such speed as “safe”. But I cannot understand what so wrong about having 150 on road as Hume highway (divided by natural strip, two lines each way, excellent surface, ample shoulders).

“You also showed a distinct shortage of grey matter in comparing the speed of planes with road vehicles.”

Please, no personal attacks – I have not provoked you, have I? :-)))))). You just miss whole point – speed does not kill, but speed treated improperly kills. I give you another examples – you can be electrocuted if treat electricity improperly. Therefore we should not use any voltage above 36V. You can fall from tall building and kill yourself – therefore we need to construct only single-story buildings. You can fall into pool and drowned – so we have to restrict pool to 0.5m. I recon you can continue list by yourself.

Cheers
Serg

Shaker you demean your self by attacking others. Serge did not attack you but you insult him. I have found Serge to have a lot o0f grey matter actually.
Pete

Well he let himself down with this statement .....

" “Speed kills” slogan invented by stupid TAC, if it would be true there will be no alive pilots by now."

Having lost a stepson due to a speeding driver it is subject that I am quite passionate about.

Shaker,

I am deeply sorry to hear about you loss and please make no mistake about my believing – each and every death on the road is unnecessarily and avoidable tragedy. However I am still in believing that above-mention slogan is wrong. Actually depends of their target – from perspective of reducing of road toll it is way too misleading while from perspective to collect more money it is spot on. It is amazed me how much emphasize they give for speeding, when at the same time I have not seen/hear from them *AT ALL* anything (I stress it again *ANYTHING*) about critical importance of good properly inflated tyres, brake and shocker absorbers condition. Lets leave alone skills and awareness discussion above! Surely poor maintained car with dodgy brakes and bald rubber in wet condition cannot handle speed as high as properly maintained one with good rubber in perfect condition, but in my strong opinion it would be wrong to restrict speed basing on poor driver who drives dodgy cars with bald tyres at the beginning of the rain on road surrounded with eucalyptuses.

Best Regards
Serg.

PS. There is another discussion – why using mobiles behind wheel so deadly wrong while eating, drinking, smoking and fiddling with MP3 player is perfectly fine? IMHO it makes no sense at all and I believe that all this activities should be banned.

LOL!!

Agree
Pete

If you wear a hat, remove that, that will help. So now you will be seen as a tightwad, driving slower to save fuel. Like the rest of us!!. Michael

Looks like Eric's piked and gone to bed but I think we need to get him to explain a few more things.
diesel 190 !!!!!! and i thought 171 bad. well it was actualyy 151 because Woolies liquor in NSW have special on where if you buy
6 wine you get 20c litre off. Good deal when you fill up with 150 litres.

Wigger!! The wine is so you forget about the high cost of the fuel!! Michael

Friend on an economy run in the car club got 82mpg in a 1200 beetle going from Brisbane to the North Coast, and was in the 1st five getting in.
He sat about a metre behind a grey hound bus all the way.

For the run we swapped co-drivers. His was white and the knuckles were frozen, took all day for him to recover. Kept mumbling about buses for some reason. :o)

Don't know if I would recommend it.

"Hey... they're going to have to drop the speed limits cos the cameras won't catch anybody at this rate."

That would be very funny Royce, if there wasn't a cold shred of credibility there. Maybe 'Low Speed Cameras' could be introduced to bump up the revenue stream?

Matt (Not a Conspiracy Theorist).

Hi Signman.
Recently had a EGT fitted. Will be heading west in July & I will try driving off the EGT.(once I get west of Tenterfield!!).
Cheers.
Vince

Oooooh Pezza, you're such a nasty man.

I buy 200 litres a week so it's not "a few dollars" More like 50
Look, I only do my 90kph thing now when there's at least a two lane freeway and when it widens out to 4/5 lanes like the M1 Nerang to Brizzy, then you're in no one's road. I agree that on single lane stuff then it's inconsiderate to drive at less than the legal limit.
The worst things is that some of the slowies dawdle along less than 100 on a single lane road and then boot it when they get to an overtaking lane. That really gives me the chits and must really p... truck drivers off.

Oh Pezza, such an angry response!!!
Yes, we are all slowing down, to save our wallets, the environment, the balance of trade, and many other benefits.

No one is talking 45 km/h. We are mostly talking 85- 95 instead of 100 - 110, and saving a lot of fuel in the process.
And my prediction is that when fuel hits $5 a litre sooner, rather than later, we will all slow even further.
If you don't like that, then tough. Get used to it.

They reduced the national speed limit in the US years ago to save fuel- that may well happen again, who knows!
Relax, and be happy!

Prezza you actually use more fuel at 45.lol
Cheers Pete