National B Eco challenge, unrealistic?

[magburner]

I have just golded the Eco challenge, to see how far you can go on a litre of fuel, and I found it to be very unrealistic. Naturally, when you accelerate, you lose fuel, but when you coast you do not use any fuel.

Perhaps I have got this wrong, but I have always assumed that even when a car was moving, and the engine was running, it consumed petrol, though it does not seem to be the case with this challenge. Also, considering that the premise of this challenge is to coast, how come the moment you run out of petrol the challenge ends? Surely you should coast until your car comes to a complete stop?

 

[eSZee]

Newer cars, for the most part, have a fuel cut and the injectors don't spray when coasting in gear . If you put the car in Neutral, that cut is not there and injectors are firing.

 

[JuiceMcGoose]

In older cars you use about the same amount of fuel when you coast with no throttle applied as you do at idle. How much gas does you car use at idle? Not much.

 

[G91V]

If you stop the car and you don't full brake, the car still goes at 14km/h more or less for a unlimited time, that's why I think the challenge ends just after having consumed all your fuel.

 

[ZZ-II]

Newer cars, for the most part, have a fuel cut and the injectors don't spray when coasting in gear . If you put the car in Neutral, that cut is not there and injectors are firing.

that's how it works! so nothing is unrealistic here

 

[BMfan]

In older cars you use about the same amount of fuel when you coast with no throttle applied as you do at idle. How much gas does you car use at idle? Not much.

According to the fuel usage gauge on a Polo it's about 0,6\0,7 L\100km with the air con off and about 1,0 with the air con on at idle but 0,0 when coasting in gear.
Did a test when i did a 1400km trip last year.

 

[magburner]

Newer cars, for the most part, have a fuel cut and the injectors don't spray when coasting in gear . If you put the car in Neutral, that cut is not there and injectors are firing.

I was not aware of this effect in newer cars, though I could see how it could be possible. The premise of the Eco Challenge, apart from maximising the use of one litre of fuel, was to instill within the user, the importance of fuel conservation in endurance races. I would not assume that the effect that you speak of in production cars ,would be present in race cars. Perhaps I am mistaken?

On a side note, if fuel conservation is a priority within GT6, endurance races could have a layer of complexity, not present in previous games.

 

[jimipitbull]

I have just golded the Eco challenge, to see how far you can go on a litre of fuel, and I found it to be very unrealistic. Naturally, when you accelerate, you lose fuel, but when you coast you do not use any fuel.

Perhaps I have got this wrong, but I have always assumed that even when a car was moving, and the engine was running, it consumed petrol, though it does not seem to be the case with this challenge. Also, considering that the premise of this challenge is to coast, how come the moment you run out of petrol the challenge ends? Surely you should coast until your car comes to a complete stop?

Are you using a DS3?

 

[bgFish]

I was not aware of this effect in newer cars, though I could see how it could be possible. The premise of the Eco Challenge, apart from maximising the use of one litre of fuel, was to instill within the user, the importance of fuel conservation in endurance races. I would not assume that the effect that you speak of in production cars ,would be present in race cars. Perhaps I am mistaken?

On a side note, if fuel conservation is a priority within GT6, endurance races could have a layer of complexity, not present in previous games.

The fuel cut-off only works in cars with a manual transmission (or something that works similarly). The engine is kept from stalling by the rotation of the wheels. In a traditional automatic with a torque converter, the engine has to be constantly fed fuel to keep from stalling.

I'm sure race cars have similar systems, but the amount of time spent coasting would be minimal if you want better lap times. Sometimes, the exact opposite happens like in blown diffuser systems in F1. The cars that had the system routed exhaust gases through aerodynamic body parts for downforce, so even when the cars were coasting, the computer would be feeding fuel into the engine to maintain the exhaust gas flow.

 

[Carlos Fandango]

Newer cars, for the most part, have a fuel cut and the injectors don't spray when coasting in gear . If you put the car in Neutral, that cut is not there and injectors are firing.

If you want an engine to run then you need air and fuel. However, when you coast or put the car in neutral, you are not trying to use the engine to move 1500kg of car so the amount of fuel needed is drastically reduced. Some cars do employ cylinder deactivation, but not all are cut (usually half).

An engine is a machine for doing work, the less work you ask it to do, the less fuel you will use.

 

[eSZee]

If you want an engine to run then you need air and fuel. However, when you coast or put the car in neutral, you are not trying to use the engine to move 1500kg of car so the amount of fuel needed is drastically reduced. Some cars do employ cylinder deactivation, but not all are cut (usually half).

An engine is a machine for doing work, the less work you ask it to do, the less fuel you will use.

I'm am not talking about cylinder deactivation, 8cyl->4cyl.
When you coast, in gear, below a certain mph, the FUEL IS CUT. If you do it in neutral, fuel consumption is more or less that of idling.

 

[rampageturke]

but when you coast you do not use any fuel.

do you even know how cars work

 

[eSZee]

do you even know how cars work

I've got some bad news for you...

 

[ironman44321]

eSZee is correct. When you take your foot off the gas in a modern car the engine is not using any fuel. The cars inertia is what keeps the engine moving.

 

[N24_VANTAGE]

eSZee is correct. When you take your foot off the gas in a modern car the engine is not using any fuel. The cars inertia is what keeps the engine moving.

So how do you think the engine stays on without any fuel?

 

[DOUQA]

According to the fuel usage gauge on a Polo it's about 0,6\0,7 L\100km with the air con off and about 1,0 with the air con on at idle but 0,0 when coasting in gear.
Did a test when i did a 1400km trip last year.

If you left the car idling at a standstill for long enough the consumption indicator would increase. It's just a measure of how far you are travelling vs fuel being injected( more specifically engine load in relation to driver torque request).

All modern engines i.e. Since the mid 90's cut all fuel on overrun so the test is accurate.

 

[N24_VANTAGE]

If anything, you use more fuel at idle than at the engines optimum speed and revs. If I left my ST sat idling for a few hours the tank would be empty. Granted, at a reduced pace compared to ragging it round a track but if I was cruising at say 57mph in 6th then I'd achieve a higher mpg than just letting her idle. Why do you think modern cars have stop start technology these days?

 

[eSZee]

Why do you think modern cars have stop start technology these days?

Idling = coasting in gear? This is news to me.

 

[ironman44321]

Here's an article by popular mechanics that does a pretty good job of explaining it

http://www.popularmechanics.com/car...oasting-in-neutral-fuel-economy?click=main_sr

"Almost all vehicles show a pulse width of zero when coasting while in gear. Zero, as in there is no fuel injected at all. Yes, the engine is turning over, the pistons are going up and down, the water pump, alternator and a/c compressor are working, so technically you can say the engine is running, sort of. But it's not consuming any fuel. And that goes for automatic or manuals."

 

[N24_VANTAGE]

Idling = coasting in gear? This is news to me.

I'm talking about idle at a standstill... In terms of coasting then you still need fuel to keep the engine running... A small amount and you have less control over said vehicle.

 

[N24_VANTAGE]

Here's an article by popular mechanics that does a pretty good job of explaining it

http://www.popularmechanics.com/car...oasting-in-neutral-fuel-economy?click=main_sr

"Almost all vehicles show a pulse width of zero when coasting while in gear. Zero, as in there is no fuel injected at all. Yes, the engine is turning over, the pistons are going up and down, the water pump, alternator and a/c compressor are working, so technically you can say the engine is running, sort of. But it's not consuming any fuel. And that goes for automatic or manuals."

I would question this to be 100% accurate because it also depends what speed you are travelling at when coasting... If you coast at a slow speed, usually below 10mph the engine is required to use some fuel. For those with an average trip computer in their car, try it. The closer you get to a stand still, the lower the mpg. Granted when traveling at a higher speed you will consume almost nothing... An infentesimale amount. So in that respect you are correct.

 

[ironman44321]

I would question this to be 100% accurate because it also depends what speed you are travelling at when coasting... If you coast at a slow speed, usually below 10mph the engine is required to use some fuel. For those with an average trip computer in their car, try it. The closer you get to a stand still, the lower the mpg. Granted when traveling at a higher speed you will consume almost nothing... An infentesimale amount. So in that respect you are correct.

Yeah in the next paragraph he talks about how the fuel injectors turn back on at low RPM but anything above 1,500 ish RPM you won't be using any fuel.

 

[N24_VANTAGE]

I call that a well settled debate.

 

[Omnis]

The fuel cut-off only works in cars with a manual transmission (or something that works similarly). The engine is kept from stalling by the rotation of the wheels. In a traditional automatic with a torque converter, the engine has to be constantly fed fuel to keep from stalling.

...Unless the automatic transmission is a fully locking one. You can also bang any auto into 2nd and 1st gear and the engine will cut fuel as it coasts to a stop. These are extreme hypermiling techniques.

 

[solidboss07]

Finally, a potential online challenge that somebody with my driving ability could win.
(Yes, James May is my favourite)

 

[Antonisbob]

...Unless the automatic transmission is a fully locking one. You can also bang any auto into 2nd and 1st gear and the engine will cut fuel as it coasts to a stop. These are extreme hypermiling techniques.

Something I do, mostly so I don't have to constantly ride my brakes, or slam on my brakes etc. But that's another reason. Around 70 Km/h my Torque converter locks up but below it's like a normal TC.

 

[xSNAKEx]

So how do you think the engine stays on without any fuel?

Because its kept moving by the wheels which turn the transmission which is attached to the engine.

...Unless the automatic transmission is a fully locking one. You can also bang any auto into 2nd and 1st gear and the engine will cut fuel as it coasts to a stop. These are extreme hypermiling techniques.

Ive always wondered if all post 1990 fuel injected automatic cars are like this? So if you stay in D the car will use fuel while coasting but if you drive it in "overdrive" 3rd or 2nd and the car is rapidly deccelarting it wont?

 

[N24_VANTAGE]

Because its kept moving by the wheels which turn the transmission which is attached to the engine.

As I mentioned earlier, thought you were referring to cars at a standstill. Apologies.

 

[Christian_C]

It's completely real and links back to fundamentals of mechanics.

If gravity is pulling your car down the hill why do you need to add more energy? (Unless you wish to go faster obviously and providing that the parasitic drag isn't slowing you down more than gravity is speeding you up).

At idle in neutral though you will use some fuel but it's small in comparison to WOT since nothing is turning the engine over aside from the energy you're putting in.

It seems a few people are forgetting that engines aren't actually constant power sources?

The GT challenge is easy enough though, just drop it in 6th and apply power as and when you need, easily get 2.5 miles +

 

[ZZ-II]

The fuel cut-off only works in cars with a manual transmission (or something that works similarly).

Wrong, that system also works with Automatic transmission.