[Petem95]

Anyone ever put this to the test? (ie reset the OBC before a motorway run and tried this with and without CC at the same speed?)

I'm sure when I apply the CC the 'MPG meter' shows slightly worse than I would get without it, but then I can't see any reason for this.

Anyone got any ideas on this?

[tyler durden]

in my experience intelligent use of CC can be as good as nonCC driving.

Over long distances on the motorway going on the flat or downhill, CC is very efficient.

The only time is loses out is uphill (even a gentle incline on the motorway). In petrol conserving driving mode I would lay off the pedal a bit and try and coast up the slope as much as poss (within reason). In practice its subtle in that I might slow down by 5-10 mph.

CC will however push as much fuel into the engine to maintain a static speed. This can be countered by gently clicking CC down when going uphill.

[SiKkBaSs]

I don't use CC. It's bound to use up more fuel over the course of a long journey.

[Petem95]

I would've expected it to be better overall, but I've not put this to the test, and I suppose it depends on the system.

When you slow down quickly using the CC stick it must actually apply the brakes, so this can't be good for MPG if it's braking on downhill bits. Otherwise it's better surely, as the speed can't creep up?

[JLR1969]

Originally Posted by SiKkBaSs

I don't use CC. It's bound to use up more fuel over the course of a long journey.

Why?? You would expect it to use the exact amount of fuel for the chosen speed and keep the speed constant

[- Paul -]

I used to find it (cc) better on my 320D - maybe to do with keeping at a constant speed tho - rather than getting a move on when bored!!

[NFS]

Originally Posted by Petem95

I'm sure when I apply the CC the 'MPG meter' shows slightly worse than I would get without it, but then I can't see any reason for this.

Hills.

People tend to allow cars to lose a little speed uphill and gain a little speed downhill - especially when cruising on motorways.

The cruise control fights this, trying to keep a constant speed and therefore uses more fuel.

[SoYank]

Cruise control here is almost useless. Anytime you turn it on some lorry driver or geriatric will pull in front of you on the four-lane and putter along at 52½ mph causing you have to drop off CC. Get around them and put it back on and some other yokel will do it again within a mile or two. About the only time I can keep CC on for any duration is through construction zones or reduced speed limit areas like Elkesley on the A1.

[SiKkBaSs]

Originally Posted by JLR1969

Why?? You would expect it to use the exact amount of fuel for the chosen speed and keep the speed constant

Yeh you're right...I'm actually being dumb.

[marcm]

Maybe this should be the next area for BMW'd Efficient Dynamics, frugal cruise control.
I'm sure it could be done. CC isnt intelligent enough to know its going up a hill, all it know is that the speed is dropping for some reason so open the taps until the speed comes back up (a bit of PID). A few more 1's and 0's in the software could make it more fuel efficient.

[M3-FAST]

I haven't used it much on the M3 but I was pretty sure in the 'vert over a long motorway distance the cruise was more economical. Prob down to the fact that it didn't accelerate to three figure speeds every time there was a gap in the traffic

[doughboy]

I just use it to avoid speeding when bored on the mway.

Great in 50mph mway average speed zones too, set at 55, go past everyone but knowing you'll be fine....

Is is pretty frugal set at say 70, but when you start using it at 90, then uphill you'll be into low tens mpg IMO.

I often preset it at 35, then when approaching a 30 limit just re-select it, the car brakes for you spot on down to 35 then maintains that speed.

[marcm]

Originally Posted by doughboy

I just use it to avoid speeding when bored on the mway.

Great in 50mph mway average speed zones too, set at 55, go past everyone but knowing you'll be fine....

Is is pretty frugal set at say 70, but when you start using it at 90, then uphill you'll be into low tens mpg IMO.

I often preset it at 35, then when approaching a 30 limit just re-select it, the car brakes for you spot on down to 35 then maintains that speed.

To be on the safe side you should set it to 33 (10% tolereance n'all that)

[doughboy]

Originally Posted by marcm

To be on the safe side you should set it to 33 (10% tolereance n'all that)

But as the BMW speedos over read (as all do), a speedo/cc 35 is an actual GPS speed of 31 ish, so well within the law.....

ACPO guidelines are +10% +2mph, so 30+3+2 = ACTUAL 35mph is the limit.

But an 'actual' 35 would be near 40 on the speedo.. so there's bags to play with...

You need a GPS speed device / camera locator, I don't use the car speed these days, especially when limits are concerned....

[ed335d]

Originally Posted by SoYank

Cruise control here is almost useless. Anytime you turn it on some lorry driver or geriatric will pull in front of you on the four-lane and putter along at 52½ mph causing you have to drop off CC. Get around them and put it back on and some other yokel will do it again within a mile or two. About the only time I can keep CC on for any duration is through construction zones or reduced speed limit areas like Elkesley on the A1.

Not unless you've got ACC - has anyone else got this? I don't think I've seen it on another car.

[fuzzer123456]

all my mega mpg figures have been using cruise control.

Better with it switched on.

[Petem95]

Originally Posted by fuzzer123456

all my mega mpg figures have been using cruise control.

Better with it switched on.

What sort of figures have you been seeing Fuzzer, and at what speeds?

[SoYank]

Originally Posted by ed335d

Not unless you've got ACC - has anyone else got this? I don't think I've seen it on another car.

With ACC the car is doing all the work but still going up and down, up and down, up and down, ad infinite making it pretty useless as a fuel conservation device. ACC is only good here if there is little traffic in front.

[jimmylimmy]

Originally Posted by ed335d

Not unless you've got ACC - has anyone else got this? I don't think I've seen it on another car.

if only my ACC would steer too, then i could have a nap!

[SoYank]

Originally Posted by jimmylimmy

if only my ACC would steer too, then i could have a nap!

Four guys rent a Winnebago for a vacation across Wyoming and Montana. A couple of miles outside Cheyenne, three are sitting in the back playing cards. The driver gets out of the seat and walks back to the others and says, "Deal me in." One of the card players asks who's driving. The driver-no-longer-driving says, "Oh, no problem. I put it on cruise control."

[simples]

Originally Posted by SoYank

Cruise control here is almost useless. Anytime you turn it on some lorry driver or geriatric will pull in front of you on the four-lane and putter along at 52½ mph causing you have to drop off CC. Get around them and put it back on and some other yokel will do it again within a mile or two. About the only time I can keep CC on for any duration is through construction zones or reduced speed limit areas like Elkesley on the A1.

yup, gotta agree here. get this problem all the time, so tend to leave it off.

[foxy-367]

I think the argument as to whether its more economical or not depends on the type of CC you have on the car. As mine isn't the auto braking version as found on 6 cylinder models it gains the MPG on downhill sections as the CC seems to back off a touch as you would if you were driving it manually.

I use cruise all the time driving a 117mile yomp up to Carlisle every couple of days for work at 6 in the morning. Perfect. Its only every so often when it needs switching off. Motorway inclines shouldn't affect the mpg too much as they are designed to be flatter than A-road gradients. At an indicated 80mph (approx 77mph on the sat nav) I get about 47-49 mpg maybe a touch more. That also includes going over Shap which is the steeper of the motorway gradients.

There are two things with CC, one is the average speed sections and maintaining the speed through there make it really good at keeping your license clean. The other is you notice how many people can't modulate their speed very well as you play overtake tennis 5 or 6 times!!!!