What is coasting

[Chili]

On my 2014 cla dash display i have a percentage screen that has acceleration, constant and coasting. I can get it upto 100% status which i guess is a good place, however i am curious about the coasting in an automatic car and how its achieved correctly, for example on my way to work i have a steep down hill stretch of road i tend to just lift my foot off the accelerator and let the car just run itself down hill, is this coasting in an auto?
Accelerator i have not quite worked out what makes that bar go up for example if i floor it then the bar goes down so clearly i am not doing that correct lol. i must add sometimes when i do attempt this coasting thing the cars feels like it is applying the brakes ever so slightly there is abit of resistance, maybe thats just my imagination.
this is my 1st merc and loving it so far.
cheers

 

[geoffus]

You are doing it correctly, its all about smooth driving for best economy. When you are cruising and feel you are going down hill then just back off a little, I also do this when coming to junctions or leaving a motorway for instance, leave the braking as long as you can rather than rushing to a stop.
I always turn off cruise control in these situations as the car may try to brake and maintain its speed when coasting down a hill.
I came back from Sunny Skegness on Friday and followed a car that insisted on braking every time we came to a long sweeping bend, only to then accelerate through it, wasting energy rather than coasting through.

 

[Chili]

You are doing it correctly, its all about smooth driving for best economy. When you are cruising and feel you are going down hill then just back off a little, I also do this when coming to junctions or leaving a motorway for instance, leave the braking as long as you can rather than rushing to a stop.
I always turn off cruise control in these situations as the car may try to brake and maintain its speed when coasting down a hill.
I came back from Sunny Skegness on Friday and followed a car that insisted on braking every time we came to a long sweeping bend, only to then accelerate through it, wasting energy rather than coasting through.

cheers for the reply i tend not to brake if i can help it the kinetic energy keeps the car going, like wise i cruise to a halt and turn off cruise control.
do you feel any kind or drag/resistance as thought the brakes are anticipating the next move??

 

[JHS]

I came back from Sunny Skegness on Friday and followed a car that insisted on braking every time we came to a long sweeping bend, only to then accelerate through it, wasting energy rather than coasting through.

Welcome to my world! During "the season" we are plagued by either wanabe race drivers or "sh1t a bend! must brake!".
Roll on winter.

 

[Gbrowncls55]

I remember being told years ago that every time you brake you harm your fuel consumption. Which when you think about it is obvious as you are wasting the fuel used to create the nomentum you have just aborted. So within the bounds of safety brake as little and as gently as possible. Coast when you can down hill and cut your speed on the motorway from say 75 to 65. Not much difference but in my car it equates to an extra 5 mpg.
This is of course all very interesting....for a bit. But it also gets very boring so generally I just drive the car but without my pants on fire (usually)

 

[MEMERC7]

I remember being told years ago that every time you brake you harm your fuel consumption. Which when you think about it is obvious as you are wasting the fuel used to create the nomentum you have just aborted. So within the bounds of safety brake as little and as gently as possible. Coast when you can down hill and cut your speed on the motorway from say 75 to 65. Not much difference but in my car it equates to an extra 5 mpg.
This is of course all very interesting....for a bit. But it also gets very boring so generally I just drive the car but without my pants on fire (usually)

Using a petrol auto 300 SLC & departing 6am I once drove 2 hours to a car event entirely on dual-carriageways & motorways & never went below 70mph & often went much faster (!). I used half a tank of petrol. Out of curiosity returning by the same route I never went faster than 50mph & only used a quarter tank of petrol. The latter boring & the former too risky licence-wise to repeat. I quickly returned to driving as fast or slow as I wish because the moment MPG is a concern then I either give up driving or buy any old cheap crappy diesel banger (as long as it's not a Mercedes).

 

[grober]

With a 2014 CLA You will have in effect a dual automated clutch manual gearbox-- like VAG's DSG ----no torque convertor losses involved

 

[Benz2fast4u]

On my 2014 cla dash display i have a percentage screen that has acceleration, constant and coasting. I can get it upto 100% status which i guess is a good place, however i am curious about the coasting in an automatic car and how its achieved correctly, for example on my way to work i have a steep down hill stretch of road i tend to just lift my foot off the accelerator and let the car just run itself down hill, is this coasting in an auto?
Accelerator i have not quite worked out what makes that bar go up for example if i floor it then the bar goes down so clearly i am not doing that correct lol. i must add sometimes when i do attempt this coasting thing the cars feels like it is applying the brakes ever so slightly there is abit of resistance, maybe thats just my imagination.
this is my 1st merc and loving it so far.
cheers

Spot on. Welcome to the world of Mercedes
How long have you had the car for?

 

[Benz2fast4u]

Using a petrol auto 300 SLC & departing 6am I once drove 2 hours to a car event entirely on dual-carriageways & motorways & never went below 70mph & often went much faster (!). I used half a tank of petrol. Out of curiosity returning by the same route I never went faster than 50mph & only used a quarter tank of petrol. The latter boring & the former too risky licence-wise to repeat. I quickly returned to driving as fast or slow as I wish because the moment MPG is a concern then I either give up driving or buy any old cheap crappy diesel banger (as long as it's not a Mercedes)

Out of curiosity, why would you not buy a Mercedes Diesel?

 

[geoffus]

I quickly returned to driving as fast or slow as I wish because the moment MPG is a concern then I either give up driving or buy any old cheap crappy diesel banger (as long as it's not a Mercedes).

You sir are in a very fortunate position to not worry about the ridiculous cost of fuel.
Anyway I love my old crappy E250 diesel, fast and frugal.

 

[baxlin]

As I understand it coasting is when there is no engine braking, as if in neutral.

I no longer have a Mercedes, but in Eco mode on my DSG auto Skoda, when lifting off the gas, ‘coasting’ is displayed, and the revs drop to tickover level. In ‘normal’ mode, engine braking is as expected on the overrun.

IIRC on my old late 80s Vauxhall Carlton CD with a 3-speed auto box there was no engine braking when in D.

 

[Chili]

Spot on. Welcome to the world of Mercedes
How long have you had the car for?

since end of jan this year

 

[ALFAitalia]

Its funny (to me ) that theses cars are engineered with coasting in mind to save fuel....as it wont. Coasting is a manual will have you failing your driving test and if its proven that you were coasting when you had an accident they will argue that you were not in full control of your vehicle.....

Drivers face £1k fines for 'coasting' in cars in misguided attempt to save fuel

Drivers can be disqualified if they are involved in a crash while 'coasting' - the practice of driving a car in neutral or with the clutch pressed down in a bid to 'save fuel'

www.mirror.co.uk

What is coasting and why is it bad? | startrescue.co.uk

Find out why coasting is a potentially dangerous practice and why in a modern car it won’t actually reduce your fuel consumption.

www.startrescue.co.uk

 

[E55BOF]

Depends how you define coasting. Above a certain rpm (can't recall what it is) if the engine is on the overrun it will use no fuel at all, but that of course reduces your speed, whereas if you allow a manual car to run down a long steep hill in neutral the car will accelerate, and though the engine will still be using idling fuel, the extra kinetic energy you gain will more than offset the tiny amount of fuel you use. (I don't think you can do this in a torque converter automatic).

(I, too, do not need to worry about the cost of fuel, but it was not always so).

 

[BigJase88]

As I understand it coasting is when there is no engine braking, as if in neutral.

I no longer have a Mercedes, but in Eco mode on my DSG auto Skoda, when lifting off the gas, ‘coasting’ is displayed, and the revs drop to tickover level. In ‘normal’ mode, engine braking is as expected on the overrun.

IIRC on my old late 80s Vauxhall Carlton CD with a 3-speed auto box there was no engine braking when in D.

Same applies in a CLA in Eco mode. Foot off the gas and the car revs will drop to idle. [Auto]

 

[Dryce]

Its funny (to me ) that theses cars are engineered with coasting in mind to save fuel....as it wont. Coasting is a manual will have you failing your driving test and if its proven that you were coasting when you had an accident they will argue that you were not in full control of your vehicle.....

Back in the day when I was young then coasting down the long inclines on some highland roads was not unsual.

Manual box. Put it in neutral. Even switch off the engine.

I really don't recall seeing it done much after the mid seventies. It was certainly increasingly frowned up because of the risk of lack of servo assistance on an descent with the engine off or on idle. And switching off on the move would be perceived as riskier as steering locks became common. Also people started driving faster on some of these roads.

As regards coasting for special purposes - I have - in the past - seen the recommendation that you put an automatic box into neutral in snow or ice when trying to come to a halt.