On the highway: Driving fast or not?

[Christophe]

Ah I had 1/2 of the correct answer then

[Obamot]

[Joke mode: ON] With 1/2 you can blow into the ball without fear

80 on the way to left and 60 to right apparently

http://www.explic.com/5586-autoroute.htm

Seeing what is happening in France, I would have sworn the opposite. Besides, many of those who were on the left went to the right to go faster ... Until Roccard makes us speeding ...

[candas1]

Laurent Ruquier out of this body

[Michel Kieffer]

At constant speed, from what speed does aerodynamics predominate?

Following the question of Citrus on the forum "The car of the future", it seems interesting to relay here the following information:

Next page 12 “ useful energy to moving a car » http://cocyane.chez-alice.fr/energie.html :

Useful power (Pu) = Pua + Pur + Pug = ½.ro.v3.S.Cx + Cr.mgv + m.accelerate.v
Constant speed => the last term = 0, which gives us: Pu = ½.ro.v3.S.Cx + Cr.mgv

The limit is reached when Pua = Pure, that is: ½.ro.v3.S.Cx = Cr.mgv
… And we get: v = square root of Cr.mg / ½.ro.S.Cx

Application:

With an average current car (see data on page 28 of the document “useful energy…), we get 76 km / h

With a very light car (see data on page 30 of the document “useful energy…) but without modifying the aerodynamics, we get 54 km / h

With a hyper-optimized futuristic car (RENAULT VESTA from the 80s!… See data on page 31 of the document “useful energy…), we get 75 km / h

Michel

[Alright]

Hello
I do not at all agree with you Did67, I have a car substantially equal to the current one, a 605 with 2l engine equipped with LPG, on my usual route I have the highway or I drive at 130, the periph limited to 90 recently and where I continue to drive 110 when I can then villages where I drive 50 and departmental where I drive 90!
well I did the test on several full ones while respecting the speed limits and lowering on the highway to 110 and my consumption dropped by 0.4l: insignificant! the problem is that wanting to limit too much creates traffic jams or ultra polluting slowdowns even at times when there were none! No offense to the limiters: I am a Toulouse Perif user and since this limitation it is the big bazaar every morning! We want to be made to believe that it runs better: wrong!
I drive LPG out of ecological conviction but I am for progress too and progress is to go from point A to point B as quickly as possible. well we know how to do it but we prefer to reduce the speed for financial purposes: the sarkosettes in blue tunics will bring in more money and the oil lobby will always put their pockets in it. here is the truth !!

[I Citro]

Hello
I do not at all agree with you Did67, I have a car substantially equal to the current one, a 605 with 2l engine equipped with LPG,
... well I did the test on several full ones while respecting the speed limits and lowering on the highway to 110 and my consumption dropped by 0.4l: insignificant !!

I too do not agree with you.
Reducing its speed very significantly decreases consumption.
You have an atypical vehicle, what is the LPG assembly. (aspirated, injection, what brand?)
How do you measure consumption. (on-board computer or rule of 3 between 2 refills)
What is your actual consumption per 100km, announcing less 0.4L does not mean anything.
How is your vehicle maintained.
I set my valve game before going on vacation, the operation with LPG was transformed ... and the consumption dropped significantly.

Finally, on the highway, the engine of your sedan turns too fast which degrades consumption a little more. Ideally, it should be mounted on the LPG of the diesel gearboxes pulling longer.
The best engine to be fitted with LPG would be the diesel engine, but French regulations do not allow it except for buses and heavy goods vehicles.

[Obamot]

It amuses me because apart from the tanks (and the like) the individual car with atomospheric engine running on petroleum must be the most polluting means of transport in the world. So at a time when many governments are going "green" they should cry "haro" on this type of car.

So even at 90 km / h ...

Useful power (Pu) = Pua + Pur + Pug = ½.ro.v3.S.Cx + Cr.mgv + m.accelerate.v
Constant speed => the last term = 0, which gives us: Pu = ½.ro.v3.S.Cx + Cr.mgv

The limit is reached when Pua = Pure, that is: ½.ro.v3.S.Cx = Cr.mgv
… And we get: v = square root of Cr.mg / ½.ro.S.Cx

[joke mode: ON] The photos above show that the car can become ecological by dissipating the energy it has stored. In addition, each crashed car will never consume oil while driving.

So on the highways, do not hesitate, roll at an open grave.

Laurent Ruquier out of this body

Do I seem to be joking?

[Did67]

I do not at all agree with you Did67, I have a car substantially equal to the current one, a 605 with 2l engine equipped with LPG, on my usual route I have the highway or I drive at 130, the periph limited to 90 recently and where I continue to drive 110 when I can then villages where I drive 50 and departmental where I drive 90!
well I did the test on several full ones while respecting the speed limits and lowering on the highway to 110 and my consumption dropped by 0.4l: insignificant!

It's not as contradictory as you describe it.

I was talking about stabilized speed. And remember. But basically, my consumption on a flat road, at steady speed (no acceleration) varies roughly by one l / 100 km when I go from 90 to 110 and again as much when I go from 110 to 130.

But the average speeds recorded on a full tank are always "composite": there are stops, restarts, braking, overtaking, climbs, descents (depending on whether you brake or lift your foot long before the turn, etc ...). All this smooths the economy made by going from 130 to 110 in stabilized speed, for example.

Take your test over a long distance ... 300 km of the same motorway at 110 stabilized then the same 300 km at 130 stabilized. That was the initial question: "whether or not to drive fast on the motorway".

[Did67]

Finally, on the highway, the engine of your sedan turns too fast which degrades consumption a little more. Ideally, it should be mounted on the LPG of the diesel gearboxes pulling longer.

Same observation. My C5 "grinds", while on LPG, you have to drive it like a Diesel. I am correcting myself: I have a long climb before arriving home. I tended to take it in 3rd gear and "spin" the engine (approximately 3 rpm). Since I go up in 500th (while "struggling" apparently, at 4 rpm less!) The instantaneous consumption displayed has dropped by around 1000/18 to around 20 l / 14 km.

In a previous post, I corrected myself, emphasizing this point.

I bitterly regret not having looked for the same car with the 6-speed gearbox option (it exists). I miss the 6th terribly to pull longer at reasonable speeds (110 km / h) ... If it was to be done again ... Notice to those who are buying ...

[nlc]

I have a long climb before arriving home. I tended to take it in 3rd gear and "spin" the engine (approximately 3 rpm). Since I go up in 500th (while "struggling" apparently, at 4 rpm less!) The instantaneous consumption displayed has dropped by around 1000/18 to around 20 l / 14 km.

I had made the same observation on my laguna essence. We have the impression that it hurts, it is a bit the case because if you press the car does not advance, but if there is no need to gain speed, then we gain a lot in consumption.