[NFS]

Originally Posted by dxb335d

In all these years, and all those miles. Ive NEVER once used Cruise control.

Why not?

[dxb335d]

Why would I ever want to. I like to ''press-on'' all of the time. Im never in a position to use it.

I never sit at 80-85mph constantly. More like 80-100-80-1xx-100-80 etc.

[E902717]

Originally Posted by dxb335d

Why would I ever want to. I like to ''press-on'' all of the time. Im never in a position to use it.

I never sit at 80-85mph constantly. More like 80-100-80-1xx-100-80 etc.

So you're the one causing the bloody traffic jams constantly speeding up and slowing down...

[dxb335d]

Originally Posted by E902717

So you're the one causing the bloody traffic jams constantly speeding up and slowing down...

Nah Ive never done that. I always nail away from everyone. I never drive rush hour either.

Only time Ive causes issues is with other E90post members on the AutoBarn, when three lanes, three abreast we slow down to 50-60mph for some rolling races. Speed up to 150, then slow down and they all catch up again, before we roar off again

[E902717]

Originally Posted by dxb335d

Only time Ive causes issues is with other E90post members on the AutoBarn, when three lanes, three abreast we slow down to 50-60mph for some rolling races. Speed up to 150, then slow down and they all catch up again, before we roar off again

Glad to see you are trying to improve our relationship with the Germans

[Wh|t3R@bb|t]

Originally Posted by TMP

But guys, is this a fair comparison..... If you are slowing down uphill, your avergae speed will be lower compared to the CC average speed?

So, if you set your CC to match the lower average speed in your test, its MPG would also improve?

True, but in terms of overall effeciency, surely letting the car do less work is more effecient and ultimately will have an effect on mpg. Like Pete said, the car will brake to maintain speed downhill, whereas I will keep the gas the same so would increase speed but the momentum/effeciency debate would say its better. And I bet the average speed isn't much different...

Having looked at my MPG meter when on CC, you can see its constantly braking, adding revs, breaking and causing the MPG to fluctuate. Whereas using my steady right foot, its stays pretty constant.

The only true test, perhaps as you ppint out, would be to get a flat road and stick at 80 with both foot and cruise control. Compare results.

Then find an undulating road but maintain constant speed uphill and downhill using both foot and cruise control. Compare again.

Anyone got the time to do the above? I haven't and being up North most roads go up and down and rarely flat. Would have been easy if I were back in Peterborough. Those flat fen roads.

Either way, I do use my cruise control but not in any belief it is more cost effecient. Although perhaps, cruising at 80ish (speedo) would mean I am less likely to get a ticket than if I am manually controlling my speed and overtaking annoying badly driven Exec cars like PAssat TDI's.

[beemerbird]

Originally Posted by E902717

Prefers the finer things in life Helen

Hmm, that's been said about me by him but in a 'bloody expensive woman' kind of way. I'm not forcing him to stay.

Originally Posted by dxb335d

I prefer using my footsie

Carl, I'm totally with you on this one. Of my last 7 cars, only the Porka T did not have cruise control fitted........you know what, I never missed it. Used it ad hoc on the Cayman in France but ended up taking it off, couldn't be doing with it.

If I'm that bothered about mpg then I'd drive something with a much smaller engine. The car uses the amount of fuel it does simple as that, and with bigger engines as soon as you 'floor it' and drive the car how it should be driven, the mpg plummets anyhow.

[NFS]

Originally Posted by beemerbird

If I'm that bothered about mpg then I'd drive something with a much smaller engine. The car uses the amount of fuel it does simple as that, and with bigger engines as soon as you 'floor it' and drive the car how it should be driven, the mpg plummets anyhow.

Cars use more petrol with cruise on.

[HighlandPete]

Originally Posted by TMP

But guys, is this a fair comparison..... If you are slowing down uphill, your avergae speed will be lower compared to the CC average speed?

So, if you set your CC to match the lower average speed in your test, its MPG would also improve?

No... you drive to get an average the same as the fixed cruise setting. For example, if you set to 70mph with cruise on, you will be aiming at the same average, even if you drop a couple of mph on the up hill and increase a couple on the down hill. It is an economy driving technique, using hills to improve mpg. So comes out better than a fixed cruise speed.

On the flat it is obviously the same, if you are a good and steady driver.

Now in an auto you also have the lock-up clutch to deal with on the cruise. You can be much more fuel hungry, if you hold a speed where on each incline the lock-up clutch disengages and the torque converter starts working and efficiency drops. The trick is to drive so that this doesn't happen, you keep direct drive and the economy at its best. Cruise will just maintain speed, using the torque converter range and even changing gear if necessary.

HighlandPete

[HighlandPete]

Originally Posted by Wh|t3R@bb|t

The only true test, perhaps as you ppint out, would be to get a flat road and stick at 80 with both foot and cruise control. Compare results.

Then find an undulating road but maintain constant speed uphill and downhill using both foot and cruise control. Compare again.

Anyone got the time to do the above?

Yes done this sort of thing over the years in different cars. Good road to do it, is the M74. Glasgow to the M6 has plenty of variety in road undulations and steeper inclines to get some good results. My 540i auto would be about 2 - 3mpg (4.4l V8 remember) less efficient on the cruise as holding the road speed meant the gearbox was flexing, whereas on the foot you could just ease the load and hold lock-up 5th. 3mpg on the 540i would be at least 5% more fuel hungry on cruise, for the same average speed.

HighlandPete

[TMP]

Originally Posted by HighlandPete

No... you drive to get an average the same as the fixed cruise setting. For example, if you set to 70mph with cruise on, you will be aiming at the same average, even if you drop a couple of mph on the up hill and increase a couple on the down hill. It is an economy driving technique, using hills to improve mpg. So comes out better than a fixed cruise speed.

On the flat it is obviously the same, if you are a good and steady driver.

Now in an auto you also have the lock-up clutch to deal with on the cruise. You can be much more fuel hungry, if you hold a speed where on each incline the lock-up clutch disengages and the torque converter starts working and efficiency drops. The trick is to drive so that this doesn't happen, you keep direct drive and the economy at its best. Cruise will just maintain speed, using the torque converter range and even changing gear if necessary.

HighlandPete

So all that sounds a lotta hassel for 1.5mpg

I use CC all the time and it frees up a few brain cells to think about soemthing more constructive than mainting speed . Of course, if I want to press on CC stays off.

I have an ED auto and in 6th I have never noticed lock-up disengaging and revs rising as a result - it gets stella mpg at 70-80mph on CC.

[HighlandPete]

Originally Posted by TMP

So all that sounds a lotta hassel for 1.5mpg

I use CC all the time and it frees up a few brain cells to think about soemthing more constructive than mainting speed . Of course, if I want to press on CC stays off.

I have an ED auto and in 6th I have never noticed lock-up disengaging and revs rising as a result - it gets stella mpg at 70-80mph on CC.

True, if you don't already drive the way I've highlighted, then it will be hard work, but for someone who's been driving 40 years it is second nature. Strange as it may seem, driving for economy was more important for most drivers, years back, than it appears today.

I've done it just to see what the difference is, sama as I've played with driving 100 miles or so, to the Isle of Skye, using auto vs. driving using steptronic, to see what is more efficient. That comes out virtually identical on the OBC.

The 6-speed autos are more efficient anyway, so even harder to get more economy by driving 'manual' style.

HighlandPete

[1 AKY]

I use cruise a lot when driving south to north and then back again at the weekends and it saves my aching knees.

I would concede that using CC downhill does kill the fuel efficiency but I'm too lazy to switch it off and would rather concentrate on the road ahead than the speedo, knowing that I'm doing a constant 'safe' speed.

As for where I put my right foot, depending on the amount of traffic and road conditions etc., it's usually next to the brake.....just in case.

[Jules6]

Originally Posted by 1 AKY

I use cruise a lot when driving south to north and then back again at the weekends and it saves my aching knees.

+1
I do some long journeys and my right knee used to ache before life with cruise control.