[Roman]

Hi everyone,

Great to see so many i30 enthusiasts in one place!! 

I bought my SLX (manual) a few weeks ago. The other day I tested the cruise control and it worked well. I read the manual too, just in case I need to know anything else.

Anyway, I got a bit of a shock when I accidently pressed the cruise control while in neutral, the engine overreved which made a pretty big noise; I quickly pressed the OFF button, but it really scared me a bit. I wonder if the engine could've been damaged too... 

I haven't called the service yet, but this should not be possible, what do you think?

[Ugly Mongrel]

Welcome to the club, R.S. I'm sure you'll enjoy the forum as much as you'll enjoy your new car.

An interesting first post. I've never read any posts on the forum about this problem. There are a lot of knowledgeable members in the club, so someone may answer your query. I'll give my cruise control a try later today and re-post.

[Roman]

Thanks mate, maybe I should've added that the car was in motion (doing about 60kms/h).

cheers

[Ugly Mongrel]

Thanks mate, maybe I should've added that the car was in motion (doing about 60kms/h).

cheers

Roman, why were you in neutral at 60kph??

[AlanHo]

I just tried it in my car. The engine does indeed rev up as described by Roman.

I accelerated to 50 mph and set the cruise on. I then de-clutched to put the car in neutral (the cruise disengaged upon pressing the clutch)

I allowed the car to coast until the speed dropped to 25 mph and pressed the cruise "resume" button.

The engine then started to increase revs. Knowing that this might happen - I was poised to disengage the cruise by depressing the clutch quickly before the engine reached 2500 rpm.

However - I should point out that this is the first time that I have let the car coast in neutral - I see no point in doing so. Especially with my diesel which uses no fuel on the over-run because the car is "pushing" the engine. When coasting in neutral the engine uses fuel to keep itself at idling speed. Anyway - I regard coasting as bordering on unsafe - you have less control of the car.

[rustynutz]

Thanks for testing that out, Alan....

[Ugly Mongrel]

I tried this on my auto. Cruise control on, doing 60km. Dumped it into neutral, cruise control disengaged immediately. While in neutral I couldn't re-engage cruise control.

[Roman]

Thanks Alan, thanks Ugly.

And that's how it should work on a manual too. The cruise should not be allowed while in neutral.

Anyway, at least I know it's not just my baby's fault 

I very often let the car coast on neutral (in traffic when reaching red lights, driving downhill (not too steep tho) or any other occasion that I regard as safe in the circumstances). I'm pretty sure it saves the juice, at least on petrol (not sure about diesel, as Alan pointed out it would not save any).

I am aware that you lose control having it in neutral, therefore I only coast when safe.

Again, I'm really glad you guys provided an answer so quickly, very much appreciated!!!   

[Ultralights]

My old Subaru did the same thing, but don't worry about damaging the engine, it has a rev limiter at its redline to prevent such damage.

[Ugly Mongrel]

No worries Roman, glad you've got it sorted. A bit of advice though...it's NEVER safe to coast in neutral. If you are in the habit of doing it you really should try to get out of the habit. The possible consequences are not worth any perceived fuel savings.

[Dazzler]

No worries Roman, glad you've got it sorted. A bit of advice though...it's NEVER safe to coast in neutral. If you are in the habit of doing it you really should try to get out of the habit. The possible consequences are not worth any perceived fuel savings.

 

[constipated]

I'm pretty sure it saves the juice, at least on petrol (not sure about diesel, as Alan pointed out it would not save any).

There are NO petrol savings either.

Modern cars cut the fuel supply as soon as the ECU senses zero throttle and that the car is continuing to move.

At that point eg going down a hill in gear, the momentum of the car keeps the engine turning and no fuel is used. You see this in cars with instantaneous fuel consumption trip computers. The reading goes to 0.0 L/100km.

However if you are in neutral down a hill or at a set of lights, a small amount of fuel needs to be burnt to keep the engine running. You don't have the cars momentum in this case.

So next time you are going down hill, keep it in gear. And when coasting to lights, keep in gear till the last bit, ie before the car reaches stall speed.

[Ugly Mongrel]

Good comment beerman. Coasting in neutral is a bit like left foot braking. Dangerous , pointless and a waste of time.

[neoto]

... and the waste of fuel. Instead of saving fuel you do the opposite.

[Roman]

Hmmm, thanks for the comments, will discuss with my mates. As far as I know, most of them flick it to neutral, so does my dad (he drives many kms every day, never had an accident...).

constipated, you mentioned "modern cars cut the fuel supply..." - does this include the i30?

Also, I find it a bit hard to believe that it would not save some petrol. When I drive down a hill in the 5th at 2500 rpm (foot off the fuel) - it must be using more petrol than having it in neutral at 750 rpm. Regardless whether safe or not, wouldn't you agree??? Or does it makes sense just to me? 

[rustynutz]

Good comment beerman. Coasting in neutral is a bit like left foot braking. Dangerous , pointless and a waste of time.

Ok, I'll bite....what's wrong with left foot braking?   

I've done it many times when I've owned an Auto....

[Shambles]

constipated, you mentioned "modern cars cut the fuel supply..." - does this include the i30?

..When I drive down a hill in the 5th at 2500 rpm (foot off the fuel) - it must be using more petrol than having it in neutral at 750 rpm...

The fuel supply is completely cut, so slowing down using engine braking is infinitely more fuel-efficient than coasting in neutral

[rustynutz]

Hmmm, thanks for the comments, will discuss with my mates. As far as I know, most of them flick it to neutral, so does my dad (he drives many kms every day, never had an accident...).

Surely you and your mates were told not to coast up to intersections etc when you learnt to drive?

it's just one of the errors examiners watch out for when you go for your licence....

[rustynutz]

Also, I find it a bit hard to believe that it would not save some petrol. When I drive down a hill in the 5th at 2500 rpm (foot off the fuel) - it must be using more petrol than having it in neutral at 750 rpm. Regardless whether safe or not, wouldn't you agree??? Or does it makes sense just to me? 

http://www.popularmechanics.com/cars/alternative-fuel/news/coasting-in-neutral-fuel-economy

[eye30]

However - I should point out that this is the first time that I have let the car coast in neutral -

I was taught NEVER EVER coast in neutral. 
I believe it would be a failure during the practical test.

There could be a time when you have to get out of a situation pronto and if you are in neutral then time may not be on your side.

[AlanHo]

However - I should point out that this is the first time that I have let the car coast in neutral -

I was taught NEVER EVER coast in neutral. 
I believe it would be a failure during the practical test.

There could be a time when you have to get out of a situation pronto and if you are in neutral then time may not be on your side.

Why pick on me - I was conducting a one off experiment on behalf of the forum.................... 

[eye30]

However - I should point out that this is the first time that I have let the car coast in neutral -

I was taught NEVER EVER coast in neutral. 
I believe it would be a failure during the practical test.

There could be a time when you have to get out of a situation pronto and if you are in neutral then time may not be on your side.

Why pick on me - I was conducting a one off experiment on behalf of the forum.................... 

Sorry. Wasn't picking on you just using part of your quote to say I was taught to never ever coast in neutral.

 

[Ugly Mongrel]

As eye30 said, coasting in neutral is a no-no during practical driving tests.

In Queensland, if you do it for less than five seconds, it's marked as a noncritical error. If you do it five time...fail. Coast for more than five second once and - KAPOW..test over...fail.

Also rustynutz, regarding left foot braking. In Queensland, if you do it five times during the course of  a practical driving test, you will fail. If you do it once, in what the driving examiner considers to be (or may cause), "a dangerous situation"...KAPOW...test over...fail.

[rustynutz]

Also rustynutz, regarding left foot braking. In Queensland, if you do it five times during the course of  a practical driving test, you will fail. If you do it once, in what the driving examiner considers to be (or may cause), "a dangerous situation"...KAPOW...test over...fail.

In a manual it could be dangerous, but in an auto I believe it's neither dangerous, pointless or a waste of time.....

[Ugly Mongrel]

In a manual it could be dangerous, but in an auto I believe it's neither dangerous, pointless or a waste of time.....

Maybe, rustynutz, but don't try left foot braking in either an auto or a manual during a driving test or you will fail.

The reason being it is considered by road safety experts to be a dangerous practice. You either want your car to stop or not stop. With a foot on the brake and the accelerator at the same time the car can do both at the same time, and this my friend, is why it's dangerous.

I wasn't going to buy into this thread because I do all the things many here have insisted are dangerous and didn't really want to have to defend it. WRT to left foot braking in an auto though I must...

Do you ever see on the telly reports of some old buggar or a woman (yeah yeah, save it!) driving through a shop front or someones bedroom or mounting the footpath to skittle a few peds? We all have, and what does the report say? "The driver mistook the accelerator for the brake."

These all happen when starting off or parking and I submit that if people did as I do when driving an auto, and that is to use the left foot to push brake when manoeuvring, it would not happen.

This not only ensures that the correct pedal is pushed IMO but gives an extra degree of control in that the brake controls the speed in much the same way that the clutch does in a manual when it's being slipped. The need of the use of both feet in a manual is again IMO why pedals are not confused because the feet are automatically oriented to the pedals when you use more than one at the same time.

Of course when on the move, the right does both jobs but this is not when you are likely to be momentarily confused.

It's unfortunate that not only is this skill not taught but going by what's been said here it's even considered dangerous. 

And WRT setting the CC while in neutral; I admit to coasting down long hills in neutral and in more than 20 years of using CC have never made the error of reenabling it before putting back in gear.  To prevent that it would require a switch or sensor to detect when in neutral. That there is none tells me this is a problem that doesn't need fixing.

[Phil №❶]

All of my driving is in auto's these days so left foot braking is something I do. My reason for doing so is to evenly wear the brake pedal; rubber & shaft. Years of right foot application can & does wear these components unevenly. If you look at old vehicles the right side of the brake pedal wear can be easily seen.

If driving is mixed, auto/manual there is a possibility of brake pedal application with clutch force. I've been in a car where this happened, nearly went through the screen. Lucky we were going slow and no following vehicles. If my driving was mixed, I simply wouldn't do it. 

[Ultralights]

left foot brake,   i dont care how you do it, just please dont use the brake pedal as a footrest!     not only do i not like the smell of burning brakes (burning $$) it leaves the brake lights on! and im sure we have all driven behind someone with the brake lights on all the time..   its bloody dangerous, may as well have no brake lights at all in those cases..

and yes, in most modern cars, the brake lights will light up even if there is no pressure on the brakes themselves,  try it next time you reverse into garage or something,

[neoto]

I drive a manual and the left foot is for the clutch only.

Regarding the safety of coasting - I must point out that this can be extremely dangerous in modern cars. Servo brakes, servo steering, ESP, EBD.... all those systems are being powered by the running engine. If the engine cuts out, you loose all of them.
It is true that the engine normally does not cut out, but I had a small hole in the intake manifold that caused erroneous air flow measurement. I was running the engine on the LPG and the LPG ECU was not correctly setup and it happened quite a few times that after I applied the throttle for a short time and then release it, the ECU was not able to stabilize the rpm in idle and the engine stopped (this was mainly happening when I was stationary, but also happened quite a few times, when I was 'coasting' with the clutch pressed - either approaching a turn or changing gears for longer than usual).
I know that this is quite a unusual scenario, but the engine can stall for several reasons. If it happens during coasting, you're in trouble.

@Roman: (I can probably say that) all the cars that use the fuel injection, stop delivering fuel when you lift your foot up from the accelerator pedal (unless the engine is in really low-rev). This also holds for our Hyundais - drive with someone that has a trip computer with the instantaneous fuel consumption and you'll see it directly.

[Phil №❶]

ultralights

I guess that's to give the following cars max time to react.