[ccomley]

I usually leave teh trip comp on "Dist to empty" but I must've caught the button and find I have the little bar charts up. S for a giggle I leave them up.

The "loud pedal" one does pretty much what you'd think. Except it kind of implies you could do better when the only way to have it stay green is NOT go drive up that ill at ALL. Also dd that when you put cruise control on, that graph goes blank - like you're supposed to just assume *it* drives like a Really Good Boy all the time. Yeah right.

The brake one does what you'd expect too .If you brake, it goes yellow or red. But if you don't, you crash.

Except.

Here's wierd. The "engine speed" one at first sight you think makes sense. It goes yellow as the engine speed goes up, but really that's just reflecting you putting your foot down harder, which keeps it from changing up.

until...

I'm a fan of engine braking, if only so that I'm down to the right gear when I need it. So earlier I'm going down a hill towards a roundabout, I flick the paddles down, drop it from 7th to about 4th, engine speed is around 3k5, and it's holding the car speed nicely as we come down the hill. And the "engine speed" graph goes yellow! WHY? I'm not burning *any* fuel, (and, to boot, not wasting any brake lining). That's just pointless.

And if you go to the "driving style" page on the "eco" screen, frankly, that's bollocks too. I overtook a slow car going up a hill. For maybe six, seven seconds, the "loud pedal" was in the red, as was engine speed graph. FOR THE REST of my trip home it was solidly in the green, briefly yellow going back up that hill I mentioned. But the "average" for accelleraetion stayed well in the red for the "trip". which is borox. So I'm not sure who this data is supposed to appeal to.

 

[PaulTheWall]

Talking of the "loud pedal" has anyone else found when you floor it and then press harder there is what feels like a kick down switch

 

[Mihai]

Talking of the "loud pedal" has anyone else found when you floor it and then press harder there is what feels like a kick down switch

Hi Paul, can you please check your inbox? I've sent you a PM asking you about the "Ceramic coating" in your signature.
Sorry for off topic

 

[ccomley]

Talking of the "loud pedal" has anyone else found when you floor it and then press harder there is what feels like a kick down switch

Never felt the need to do that. Probably the kick-down switch! But I'll have used the paddles about a week before that point.

 

[PaulTheWall]

Mihai I have replied

 

[Disco Oldenburg]

Talking of the "loud pedal" has anyone else found when you floor it and then press harder there is what feels like a kick down switch

Hi Paul,
On my current car, which is a manual, this switch cancels the speed limiter when activated, so you can make an emergency get away.

Martin

 

[Moose]

I was playing with the Eco screen, I can get the brake to 5 and the accelerator to 4.9 by driving on the motorway, but the speed is low, highest I got was 91%

 

[ozsport]

I'm a fan of engine braking, if only so that I'm down to the right gear when I need it. So earlier I'm going down a hill towards a roundabout, I flick the paddles down, drop it from 7th to about 4th, engine speed is around 3k5, and it's holding the car speed nicely as we come down the hill. And the "engine speed" graph goes yellow! WHY? I'm not burning *any* fuel, (and, to boot, not wasting any brake lining). That's just pointless.

You're still burning fuel - just not as much as when you're on the accelerator. In the carburettor days it was sucked through by the vacuum created in the intake chamber... these days I imagine the injectors just squirt the bare minimum of fuel. The only time you're not using fuel is when your engine is stopped - hence stop/start technology.

As for engine braking, whilst it's certainly useful in some situations (steep mountain descents whilst towing for example) I wouldn't do it in normal driving conditions. Higher revs place higher strain on the engine which is just unnecessary driving through a roundabout. As my old man used to say, it's much cheaper to replace a set of brake pads than an engine

 

[geonic]

When you are going down a hill without using your right foot and the engine revs around 3k5 then the engine is in deceleration fuel cut-off mode. This means that no fuel is burned at all and this is standard since fuel injection became common.
It seems to me that the bar graph only measures engine revs without taking fuel consumtion into account. So it seems like the bar graph is only for entertainment.

I´m assuming the engine was in operating temperature.

 

[philn]

If you look at the instant fuel consumption on the info screen it will show that you are using fuel when going downhill with your right foot off, this is the same on all cars not just the DS, don't know the theory behind it though.

 

[PaulTheWall]

Down hill no throttle my instant fuel consumption goes to a max of 99 mpg

 

[geonic]

All my cars (non LR) show an instant consumption of zero when rolling without pushing the pedal. At least as long as the engine is slightly above idle speed and warm. Also my 14 year old BMW motorbike with fuel injection does this.

Can´t believe LR is still in the 70s of the last century

 

[Lofi]

My Mrs without trying turns everything to green. I take great pleasure in ruining that within about 5 miles of leaving the house. Is she amused. Not really.

 

[ccomley]

I'm a fan of engine braking, if only so that I'm down to the right gear when I need it. So earlier I'm going down a hill towards a roundabout, I flick the paddles down, drop it from 7th to about 4th, engine speed is around 3k5, and it's holding the car speed nicely as we come down the hill. And the "engine speed" graph goes yellow! WHY? I'm not burning *any* fuel, (and, to boot, not wasting any brake lining). That's just pointless.

You're still burning fuel - just not as much as when you're on the accelerator. In the carburettor days it was sucked through by the vacuum created in the intake chamber... these days I imagine the injectors just squirt the bare minimum of fuel. The only time you're not using fuel is when your engine is stopped - hence stop/start technology.

As for engine braking, whilst it's certainly useful in some situations (steep mountain descents whilst towing for example) I wouldn't do it in normal driving conditions. Higher revs place higher strain on the engine which is just unnecessary driving through a roundabout. As my old man used to say, it's much cheaper to replace a set of brake pads than an engine

Not true. All fuel injection systems cut off completely on over-run. No fuel is injected at all. Of course once you come to *rest* you need some fuel to keep the engine idling, and THAT is why auto-stop-start.

Revving around 2k5-3k for a couple of hundred yards doesn't stress the engine. The biggest problem with engine braking is manual gearbox users who don't blip on the downchange, so bringing the engine up to speed for the lower gear is all done by friction on the clutch plates .

 

[ccomley]

If you look at the instant fuel consumption on the info screen it will show that you are using fuel when going downhill with your right foot off, this is the same on all cars not just the DS, don't know the theory behind it though.

Nope. If you put it in "litres per hundred km" mode (euro-speak) it'll show zero. The only problem with "Mpg" when your'e using no gallons is it's a divide-by-zero error, so the "instant" figure usually just shows the largest figure the dial can show, 99 or 999.

Some cars have a hidden extra mode on the display which shows what's going on under the hood. My previous car (Astra with the 2 litre turbo engine) could do this, and showed both the rate of fuel injection in ml/sec, which went to zero when on over-run, and also an indicator for "FC" which showed "on" on over-run, and "off" otherwise. FC stands for Fuel Cut-Off.

 

[ccomley]

My Mrs without trying turns everything to green. I take great pleasure in ruining that within about 5 miles of leaving the house. Is she amused. Not really.

Bad Person!

I'm just not convinced the displays are a fully accurate measure of "economy". But it's good enough for government work.

 

[ozsport]

Not true. All fuel injection systems cut off completely on over-run. No fuel is injected at all. Of course once you come to *rest* you need some fuel to keep the engine idling, and THAT is why auto-stop-start.

There ya go I did not know that, although I did find this is only on electronically controlled fuel injection. Older mechanical fuel injection methods still injected fuel. But yes I agree it applies to the DS

Oh and also high performance applications (such as racing but may also be true of supercars - I don't know) keep the fuel going for various reasons, not least of which is to make awesome overrun exhaust flames

 

[ccomley]

There ya go I did not know that, although I did find this is only on electronically controlled fuel injection. Older mechanical fuel injection methods still injected fuel. But yes I agree it applies to the DS

Oh and also high performance applications (such as racing but may also be true of supercars - I don't know) keep the fuel going for various reasons, not least of which is to make awesome overrun exhaust flames

You're quite right, I should've excluded mechanical fuel injection systems from my blanket statement!

Yes, sports cars are different. One reason they run more fuel than necessary is a system called "anti-lag", which deliberately burns fuel to keep the turbo spinning at full speed when it would otherwise slow down or even stall due to inlet manifold pressure. But that's all rather specialised.

Cars have been using no petrol or diesel on over-run since the 70s, at least, I still remember BMW's dick-treading-on moment when they took out a full page ad in all the big papers announcing "zero miles to the gallon".