Using cruise control on motorway

demanufactured

Hi all.
I have an 04 Audi A4 1.9TDI AVANTE estate.
It's a great car very comfortable.
My daily commute is a 100 mile round trip between athlone and galway, 99% motorway.
I go between using the CC and driving normally.

Being motorway..which method is most likely to save on fuel.
I know when I'm driving normally and I hit decline the car will speed up under its own momentum. ..something it can't do on CC as it's speed is being governed.

On a flat piece of road the readout reads between 40-45 mog...on both CC and driving normally at 120kph.

I brim the tank once a week regardless of what it has in it....usually near empty.
Usually getting 650-700 miles from a tank.

ECU was remapped by previous owner.
Was 90bhp, now 140bhp

Would I be better using CC all the time or driving normally all the time?

MuppetCheck

Slightly better doing it yourself, but I prefer cruise personally.

colm_mcm

Depends on how good you are at driving efficiently. Cruise control will use a little more fuel than a careful right foot.
Cruise is so handy though. Nothing wrong with 700 miles per tank.

listermint

In the haulage industry cruise control is a must and contributes massively to fuel efficiency. Surely the same is true of smaller vehicles in long runs.

colm_mcm

listermint wrote: »

In the haulage industry cruise control is a must and contributes massively to fuel efficiency. Surely the same is true of smaller vehicles in long runs.

Nope. Cruise control can't predict dips, hills etc as well as you can so boots it to maintain your set speed.

Some ones on trucks use gps data to predict gradients and crucially select the correct gear thus saving money on fuel.

listermint

colm_mcm wrote: »

Nope. Cruise control can't predict dips, hills etc as well as you can so boots it to maintain your set speed.

The key here is motorway... What you have described does not tally really with our motorways system

sogood

I would always tend to go with cruise, for comfort and to avoid accidentally creeping above the speed limit. Any savings made using one method over another would quickly be negated by a traffic jam, use of aircon, badly inflated tyres or any other number of factors. So, 6 of 1, half dozen of the other I suppose.

colm_mcm

listermint wrote: »

The key here is motorway... What you have described does not tally really with our motorways system

We don't have hills?

Noccy_Mondy

I wish I had the opportunity to use CC often - only get to use it occasionally, so much so that I try to give it a go when on national roads, quite the experience going around the bends and such

colm_mcm

It's one thing I'd never buy a car without. I reckon its saved me a few speeding tickets too.

Phil_Lives

colm_mcm wrote: »

We don't have hills?

comparatively? No!
Most of my Colleagues in work are ticking the box for adaptive cruise control on the cars the order.
The Polo has and Corsa E will have ACC.
One of my Colleagues lives over 100km from work and dials in 160kmph and keeps the car on cruise control all the way to work every day once he hits the motorway. If the car hits heavy traffic it applies brakes and tightens belts.

Jesus.

listermint wrote: »

The key here is motorway... What you have described does not tally really with our motorways system

What?

I regularly drive to Galway from Naas and once I am past the toll booth after Kilcock I put on the cc. Am a bit heavy on the right pedal so I reckon it probably evens out on the km/l. Comfort wise the cc is brilliant.
I usually get 6.5l/100km.

djimi

colm_mcm wrote: »

We don't have hills?

Its been a while since I have had CC in a car but I dont recall my car ever "booting" it on a motorway to compensate for a gradient!

biko

I've used both CC and manual extensively and CC will use more fuel, still worth it.

dingding

djimi wrote: »

Its been a while since I have had CC in a car but I dont recall my car ever "booting" it on a motorway to compensate for a gradient!

I think the issue is that the car maintains the speed. If you let it slow down going up the hill, using less power and getting back up to speed on the down hill would be probably more efficient.

Toyotafanboi

djimi wrote: »

Its been a while since I have had CC in a car but I dont recall my car ever "booting" it on a motorway to compensate for a gradient!

ah it kind of does in fairness.

you can be pottering along on the flat at 90/ 100km/h and if a relatively sudden incline arises you can feel the car going to very close to wide open throttle to stop itself bogging down without having to shift gear.

you can also watch it on the trip computer, if you have an instantaneous mpg readout, when using cc if you meet a large incline etc you could often see your mpg half as you enter the hill.

Noccy_Mondy

djimi wrote: »

Its been a while since I have had CC in a car but I dont recall my car ever "booting" it on a motorway to compensate for a gradient!

If you can get your hands on a car with it sometime, try it on a stretch of "bad" road that you are familiar with driving on manually, when it comes to a hill or hollow you will get a boost.

The Royal Scam

[Deleted User] wrote: »

I regularly drive to Galway from Naas and once I am past the toll booth after Kilcock I put on the cc. Am a bit heavy on the right pedal so I reckon it probably evens out on the km/l. Comfort wise the cc is brilliant.
I usually get 6.5l/100km.

Out of interest , im going to Oranmore from Newbridge at 8 in the morning , normally go to sallins clane and onto the m4 at kilcock. Which way do you go? Oh and I drive 1700k avg a week mostly on motorways. Definitely cc, saves for me as if I dont set it for approx 130kph I end you always going up above and around 150kph

Titzon Toast

I have CC on my car but I never use it. You can't trust other motorists on the M1 most days and I'm always on my guard for some reason!

unkel

I try and use it as much as I can, but the real comfort benefits are on empty-ish motorways (not anywhere near Dublin so)

From some rough estimations, I reckon CC uses about 10% more fuel at 120km/h compared with a smooth, light, efficient and anticipating foot averaging the same speed. Still worth it though

billie1b

biko wrote: »

I've used both CC and manual extensively and CC will use more fuel, still worth it.

Have to say, mines the opposite, if I use my right foot the kilometres per tanks is 550-600, if I use the CC I can get 700 from the tank. My right foot is not that heavy either

GreeBo

dingding wrote: »

I think the issue is that the car maintains the speed. If you let it slow down going up the hill, using less power and getting back up to speed on the down hill would be probably more efficient.

So you mean sliding down on up hills because you know there is a downhill coming up?
That's not maintaining the same speed though, that's like an average which is not what does.

That method is the equivalent of letting your car freeze and then roast, averaging 20 degrees but nowhere near as comfortable as using climate control set to a constant 20.

GreeBo

Toyotafanboi wrote: »

ah it kind of does in fairness.

you can be pottering along on the flat at 90/ 100km/h and if a relatively sudden incline arises you can feel the car going to very close to wide open throttle to stop itself bogging down without having to shift gear.

you can also watch it on the trip computer, if you have an instantaneous mpg readout, when using cc if you meet a large incline etc you could often see your mpg half as you enter the hill.

How would driving manually avoid using more fuel on an incline??

Toyotafanboi

GreeBo wrote: »

How would driving manually avoid using more fuel on an incline??

for example if you were aiming to travel at a steady 100km/h:

you would anticipate the incline before you arrive upon on (which the cc doesn't) and therefore gradually ease the car up maybe 5 or 10km/h faster to compensate for the loss of momentum and speed when you meet the hill. slowly climbing from 100 - 110kmh on a level surface will use much less fuel than flooring the throttle after you have already begun the incline to try maintain speed.

also you will be able to compromise with the car during the ascent. the car may sit comfortably for a perriod with the throttle say 30% open at 90/ 95km/h and you can climb steadily, whereas with the cc on it may be using 50% or more throttle to try and maintain 100km/h steady.

all hypothetical numbers but the points are valid.

Jesus.

GreeBo wrote: »

So you mean sliding down on up hills because you know there is a downhill coming up?
That's not maintaining the same speed though, that's like an average which is not what does.That method is the equivalent of letting your car freeze and then roast, averaging 20 degrees but nowhere near as comfortable as using climate control set to a constant 20.

I think that's what he was trying to say in fairness

unkel

GreeBo wrote: »

How would driving manually avoid using more fuel on an incline??

You would gently up your speed to say 130km/h before the incline and then while climbing, let the car slow down to say 100km/h. In other words, don't overcompensate by stamping on the gas like the cc would.

Smoothness saves fuel. A lot of fuel

Edit: Toyotafanboi beat me to it :cool:

djimi

Toyotafanboi wrote: »

ah it kind of does in fairness.

you can be pottering along on the flat at 90/ 100km/h and if a relatively sudden incline arises you can feel the car going to very close to wide open throttle to stop itself bogging down without having to shift gear.

you can also watch it on the trip computer, if you have an instantaneous mpg readout, when using cc if you meet a large incline etc you could often see your mpg half as you enter the hill.

Fair enough; I cant say I ever used CC on a road that was steep enough to warrant dropping a gear. On a normal incline the car would increase throttle to the same amount as I would it I was driving the car manually, so I cant imagine it was using much more fuel, if any at all, compared to my driving style anyway!

Jesus.

GreeBo wrote: »

How would driving manually avoid using more fuel on an incline??

You speed up before you hit the incline and the momentum gets you over using less fuel than if you just hit it at the same speed and then have to put your boot on the floor when going up the hill.

Toyotafanboi

djimi wrote: »

Fair enough; I cant say I ever used CC on a road that was steep enough to warrant dropping a gear. On a normal incline the car would increase throttle to the same amount as I would it I was driving the car manually, so I cant imagine it was using much more fuel, if any at all, compared to my driving style anyway!

i'm only kind of observing it myself at the moment in a different way. on my n11 around my way there are a few steep motorway inclines and my corolla is a weedy enough 1.4 petrol.

if im on the flat doing 100km/h i'm getting around 40mpg, to try and maintain 100km/h on a long steep incline (outside rathnew for example) the instantaneous readout would drop to the mid to low 20's mpg until the road levels out again. whereas if i slow to around 85km/h (which i don't, because there's nothing worse on the motorway :P) i can keep the car in the late 30's - 40 ish mpg.

alias no.9

colm_mcm wrote: »

It's one thing I'd never buy a car without. I reckon its saved me a few speeding tickets too.

Nothing beats good old fashioned observation for avoiding speeding tickets. I'm a firm believer that speed vans (garda or gosafe) issue tickets to people who don't observe the reactions of the cars in front, and they're almost never on a road where there are no cars in front.

OT cruise control can.be frustrating on a motorway, you pass somebody, they get offended, pass you and slow down. What do you do? Cancel the cruise or pass them again?

billie1b

Jesus. wrote: »

You speed up before you hit the incline and the momentum gets you over using less fuel than if you just hit it at the same speed and then have to put your boot on the floor when going up the hill.

Your still putting the boot to the floor to speed up before the incline, thats using fuel just the same as doing it on the incline

visual

Have had few cars with CC all use slightly more fuel then driven manually.

Knowing its not as efficient as manually driving I still use it when I get the opportunity because it makes driving easier and stops me from speeding.

Toyotafanboi

billie1b wrote: »

Your still putting the boot to the floor to speed up before the incline, thats using fuel just the same as doing it on the incline

you are using much less fuel by increasing speed on the level road before the hill than you are if you don't take action until you are already climbing.

think of it as riding a push bike. which is easier on your legs?

when you see the hill in the distance do you speed up a little, change down a gear and pedal consistently up the hill

or

do you free wheel towards the hill, wait until the bike begins to slow down, crunch down a few gears and pump your legs hard to keep moving.

Y2KBOS86

Phil_Lives wrote: »

comparatively? No!
Most of my Colleagues in work are ticking the box for adaptive cruise control on the cars the order.
The Polo has and Corsa E will have ACC.
One of my Colleagues lives over 100km from work and dials in 160kmph and keeps the car on cruise control all the way to work every day once he hits the motorway. If the car hits heavy traffic it applies brakes and tightens belts.

160kmph?

Are the two of ye working in Germany?

Popoutman

The fact that manual control of the speed tends to vary about a value, where the cruise control keep to that value, means that in general it's not truly comparing like for like. If you were exact on keeping to the requested speed manually without changing any gear, you should end up very very close to the same figure you'd have seen with the CC active. Instead, most people when not using the cruise tend to keep close to a specified throttle position instead of a specified roadspeed, tends to skew the numbers a bit.

I am seriously thinking of doing the cruise retrofit to my 02 Audi estate now that the kits have dropped below €100 in price for my car - it's something that could be quite handy for the longer trips that I go on. My next car will have to have CC, and hopefully I can get it with adaptive cruise.

Toyotafanboi

Popoutman wrote: »

The fact that manual control of the speed tends to vary about a value, where the cruise control keep to that value, means that in general it's not truly comparing like for like. If you were exact on keeping to the requested speed manually without changing any gear, you should end up very very close to the same figure you'd have seen with the CC active. Instead, most people when not using the cruise tend to keep close to a specified throttle position instead of a specified roadspeed, tends to skew the numbers a bit.

very well put.

just interesting to note, in line with this thread that allowing your speed to vary by say up to 10% depending on the gradient of the road can have a dramatic effect on fuel consumption/ efficiency.

pablo128

alias no.9 wrote: »

Nothing beats good old fashioned observation for avoiding speeding tickets. I'm a firm believer that speed vans (garda or gosafe) issue tickets to people who don't observe the reactions of the cars in front, and they're almost never on a road where there are no cars in front.

OT cruise control can.be frustrating on a motorway, you pass somebody, they get offended, pass you and slow down. What do you do? Cancel the cruise or pass them again?

Pass them. If they start accellerating, blitz them into the weeds. Crank it right up. They will back off, and you reduce your speed back to where you want it. It works. I drive the vans in work a good bit as cover for the drivers. Nothing gets peoples goat up more than a van passing them out.

The Royal Scam

The Royal Scam wrote: »

Out of interest , im going to Oranmore from Newbridge at 8 in the morning , normally go to sallins clane and onto the m4 at kilcock. Which way do you go? Oh and I drive 1700k avg a week mostly on motorways. Definitely cc, saves for me as if I dont set it for approx 130kph I end you always going up above and around 150kph

I take the same route to Kilcock. Just be careful on the Kilcock to Clane stretch coming back as it's a real hotspot for the speed camera vans.

NewApproach

Anyone who doesn't use CC because of the slight extra fuel it may use, should probably just sell the car and use the bus/bicycle.

Penny pinching gone mad :rolleyes:

TimeToShine

Is it more efficient to use CC at 120-140km/h on a motorway than it is to cover the same distance on an 80km/h road? Time factor aside.

debabyjesus

demanufactured wrote: »

ECU was remapped by previous owner.
Was 90bhp, now 140bhp

It wasn't 90 in an 04 A4 for starts and doubt its 140 now either. Just use the cruise and potter along with a coffee and some tunes!

daveohdave

Indeed, someone was telling porkies there.

bidiots

daveohdave wrote: »

Indeed, someone was telling porkies there.

Considering this is a return trip:

On return the Dips would be hollows, and hollows would be dips, therefore the trip is level in total, which should make CC more efficient?

ðŸ˜

jimgoose

I use cruise-control on motorways, largely because without it she'll wander up to license-toasting speeds very easily and largely unbeknownst to me. Fuel-wise it seems efficient enough on autopilot, but I've never been arsed doing a comparison.

padd b1975

colm_mcm wrote: »

Nope. Cruise control can't predict dips, hills etc as well as you can so boots it to maintain your set speed.

Some ones on trucks use gps data to predict gradients and crucially select the correct gear thus saving money on fuel.

If set correctly, a truck will knock itself into neutral going down a hill to save fuel, once the truck increases to a pre-set speed the retarder kicks in to keep it at that speed (In my truck it's up to 15km/h above the limiter)

Once the truck starts to climb again the truck automatically goes back into the appropriate gear.

Zubeneschamali

alias no.9 wrote: »

you pass somebody, they get offended, pass you and slow down. What do you do? Cancel the cruise or pass them again?

Pass again, but not on cruise control, give it some welly.

Galway to Athlone, my record is passing the same bozo four times.

keithclancy

padd b1975 wrote: »

If set correctly, a truck will knock itself into neutral going down a hill to save fuel, once the truck increases to a pre-set speed the retarder kicks in to keep it at that speed (In my truck it's up to 15km/h above the limiter)

Once the truck starts to climb again the truck automatically goes back into the appropriate gear.

Running in Neutral uses more fuel, running in gear down a hill should use zero fuel since in an overrun condition the ECU should shut off the injectors.

Running in Neutral on a truck down in hill in Ireland you could probably get away with since Ireland doesn't really have that many hills.

In Norway/Switzerland/Southern Germany you would end up boiling the brakes.

padd b1975

keithclancy wrote: »

Running in Neutral uses more fuel, running in gear down a hill should use zero fuel since in an overrun condition the ECU should shut off the injectors.

Running in Neutral on a truck down in hill in Ireland you could probably get away with since Ireland doesn't really have that many hills.

In Norway/Switzerland/Southern Germany you would end up boiling the brakes.

Not according to the Volvo Dynafleet software my boss has installed in his trucks to monitor each driver.

If we reach a certain level of eco driving we qualify for a bonus. One of the main ways of getting this bonus is to allow the truck to 'coast' as much as possible up to junctions roundabouts etc etc and to use the foot brakes to the bare minimum.(something that would be frowned upon not so long ago with a gross weight up to 44 tons, money talks I suppose).

Bigcheeze

Have CC now but never had it until recently. Using it gives me a sensation of having less control over the car and my reaction times are increased but I'll probably get used to it.

jimgoose

Bigcheeze wrote: »

Have CC now but never had it until recently. Using it gives me a sensation of having less control over the car and my reaction times are increased but I'll probably get used to it.

Hmmm. Mine is quite usable, at any rate. A nice trick is being able to override it immediately by just standing on the loud pedal, and when you come off it it just settles back as it was. Also, operating either the service brake, handbrake or clutch disengages it instantly, as well as the actual "Cancel" button on the steering wheel.