MPG with C/Control on

[hawk20]

It is just not theoretically possible for a driver maintaining a constant 70mph (or whatever) to get any more miles per gallon than cruise doing the same thing. Both must push in just enough fuel to achieve that speed.

And if you save fuel by continually slowing up on hills and speeding up down the other side, what a nuisance for following drivers!

Cruise is for maintaining a constant cruising speed without having to keep checking the speedo and without having to keep your leg and foot in exactly the same position for long periods.

Because roads are not dead level, and winds vary, most drivers will find their speed varies somewhat. All of us have sometimes noticed how speed on motorways creeps up. Cruise saves fuel by keeping a constant speed but only if you use it when constant speeds are possible.

If not, as I posted earlier, it will accelerate hard to return to your cruising speed. That is what uses the extra fuel. So return to cruising speed yourself and then re-activate cruise.

Remember it was developed before VED went up and fuel costs went through the roof and many became obsessed with economy (naturally enough.) It was designed to maintain cruising pace and so IMO it accelerates harder than an economy minded person would find beneficial. So just use it for constant speed and then it cannot be beaten.

 

[st4]

Cruise is for maintaining a constant cruising speed without having to keep checking the speedo and without having to keep your leg and foot in exactly the same position for long periods.

It should be comfortable to do this, is your seat adjusted properly and your legs and feet positioned in a comfortable position over the pedals. Remember in an auto your left leg + foot is in the same position for the whole journey duration, unless you left foot brake

 

[hawk20]

It should be comfortable to do this, is your seat adjusted properly and your legs and feet positioned in a comfortable position over the pedals. Remember in an auto your left leg + foot is in the same position for the whole journey duration, unless you left foot brake

Not really so. You can move your left leg occasionally and give it a bit of a stretch as all orthopaedics recommend. Cruise lets you move your right leg around for a few seconds while the road is clear ahead and that is a good thing too for circulation etc.

 

[st4]

Not really so. You can move your left leg occasionally and give it a bit of a stretch as all orthopaedics recommend. Cruise lets you move your right leg around for a few seconds while the road is clear ahead and that is a good thing too for circulation etc.

Ah but you can move your right leg/foot by not using cc and still move the left leg about

 

[hawk20]

Ah but you can move your right leg/foot by not using cc and still move the left leg about

Really. To maintain a constant 70 mph do you hold the accelerator with your hand while you move your right leg around?

 

[st4]

Really. To maintain a constant 70 mph do you hold the accelerator with your hand while you move your right leg around?

You mis read me, you still adjust the throttle due to gradient canges, surface changes, corners @ 70mph Mways, never mind all the potential hazards. Having travelled a fair bit down the M6 I was always aware of the need to change my level of pressure on the throttle.

 

[flango]

You mis read me, you still adjust the throttle due to gradient canges, surface changes, corners @ 70mph Mways, never mind all the potential hazards. Having travelled a fair bit down the M6 I was always aware of the need to change my level of pressure on the throttle.

For the uninitiated this is called "acceleration sense" to maintain 70 mph will always require different accelarator pressure even on a flat long stretch of motorway. For those who don't believe me try driving at 70 mph with a sprintbooster fitted and then see what difference a little light pressure on the throttle makes. A smooth driving style with good anticipation of unfolding events will always be the most economical and safest way to drive.

 

[hawk20]

For the uninitiated this is called "acceleration sense" to maintain 70 mph will always require different accelarator pressure even on a flat long stretch of motorway. For those who don't believe me try driving at 70 mph with a sprintbooster fitted and then see what difference a little light pressure on the throttle makes. A smooth driving style with good anticipation of unfolding events will always be the most economical and safest way to drive.

And that is why humans are so bad at maintaining a constant speed and why cruise is so useful.

You can still have a smooth driving style and good anticipation of unfolding events and use cruise in the way I described earlier.

 

[flango]

And that is why humans are so bad at maintaining a constant speed and why cruise is so useful.

You can still have a smooth driving style and good anticipation of unfolding events and use cruise in the way I described earlier.

Cruise lulls you into a false state of security and lowers your level of concentration, for example when using cruise most people get too close to the car in front (unless using adaptive cruise) hoping to maintain that pre set figure and hoping the car in front will accelerate away so they don't have to brake. If you were not on cruise you would simply back off the accelerator momentarily with no loss of speed but still maintaining a safe gap.

I agree cruise is useful in the right circumstances but was designed for long American interstates not the congested excuses for motorways we have

 

[Ted]

I have to say, that apart from those stupid collapsible rear headrests on my w210, cruise control has been the most useless factory fitted accessory I think I have ever had.

 

[Shude]

I also think CC detracts from ones concentration and takes a vital part of the car control process away, and by being locked into a specific speed you can find yourself in siutations you wouldn't normally have been in...

Totally the opposite!

As the speed is a constant the cruise-control user must look to change lane rather than speed, this requires a lot of concentration and observation.

The aim of the game is to never disengage!

 

[hawk20]

I agree cruise is useful in the right circumstances but was designed for long American interstates not the congested excuses for motorways we have

Useful in Europe too. Much less traffic on motorways in France and can go ages at constant speed. Helps avoid fines!

I use cruise every day. Love it. I use it in speed limit areas when there is not much traffic. So easy to keep to a chosen safe speed without speedo watching. Good safety feature, used properly, IMO.

The limiter can be useful for speed limits too. And some prefer that.

 

[st4]

Totally the opposite!

As the speed is a constant the cruise-control user must look to change lane rather than speed, this requires a lot of concentration and observation.

The aim of the game is to never disengage!

But by adapting your speed you can merge into a different lane more smoothly in a lot of situations. I find thats actually the most restrictive aspect of CC is the inability it offers the driver to smoothly merge with other lanes by use of "accelerator sense". I find I can concentrate on whats go on about me and use my right leg to adjust the go pedal

The limiter can be useful for speed limits too. And some prefer that.

Yo beat me to it, but I find that can maybe inhibit you from accerating out of a situation. i.e. hazard in lane 1, queue of vehicles approaching from behind in lane 2, accerate to get into lane 2 infront of them otherwise "boxed in". With limiter your stuffed, and I'd chance a fine/penalty over my safety.

 

[Shude]

But by adapting your speed you can merge into a different lane more smoothly in a lot of situations. I find thats actually the most restrictive aspect of CC is the inability it offers the driver to smoothly merge with other lanes by use of "accelerator sense". I find I can concentrate on whats go on about me and use my right leg to adjust the go pedal

We're talking about MPG here.

Maintaining speed and changing lane is what saves fuel, changing speed as you suggest will burn fuel.

 

[st4]

We're talking about MPG here.

Maintaining speed and changing lane is what saves fuel, changing speed as you suggest will burn fuel.

You're not seeing the bigger picture. You might need to change speed slightly by moving lane, to avoid a hazard, rather than slowing down much more awaiting for it to move, then resuming CC. On the bigger picture being able to control your car will offer more MPG.

 

[flango]

Totally the opposite!

As the speed is a constant the cruise-control user must look to change lane rather than speed, this requires a lot of concentration and observation.

The aim of the game is to never disengage!

*** is perfectly correct proven fact by the TRRL that the use of cruise control over long distances / periods decreases concentration. You try switching lanes whilst on cruise in traffic can you do it smoothly & safely ? NO.

Aim of the game never to disengage what a dangerous game you play!

 

[st4]

*** is perfectly correct proven fact by the TRRL that the use of cruise control over long distances / periods decreases concentration. You try switching lanes whilst on cruise in traffic can you do it smoothly & safely ? NO.

Aim of the game never to disengage what a dangerous game you play!

...that can lead to dior consequences. I have driven with CC and in my experience its put me into situations that if it hadn't been engaged I would never have been in the first place. I tried CCon the M9 thru from Stirling to Edinburgh, not a long haul but enough to see that it eroded my concentration, took away the involvement of controling my car (something I enjoy) and normally I can get >50mpg on that trip, I was about 3mpg short of that. Plus I enjoy driving the car so I find it pleasurable to use the pedals.

 

[Shude]

You're not seeing the bigger picture. You might need to change speed slightly by moving lane, to avoid a hazard, rather than slowing down much more awaiting for it to move, then resuming CC. On the bigger picture being able to control your car will offer more MPG.

Please can you describe such a hazard that requires slight change of speed when doing approx 70mph?

If you are having to change speed slightly to avoid a hazard then you have not been correctly observing the vehicles and environment in front of you.

Using cruise control does not take the pedals away from you, it just maintains the speed. If you want to go faster or slower you still can

 

[st4]

Please can you describe such a hazard that requires slight change of speed when doing approx 70mph?

If you are having to change speed slightly to avoid a hazard then you have not been correctly observing the vehicles and environment in front of you.

Using cruise control does not take the pedals away from you, it just maintains the speed. If you want to go faster or slower you still can

off the top of my head yes

The car infront of you is doing 60 MPH its 500 yds away but, you're gaining on him quite rapidly, in your mirrors the queue of traffic is gaining on you, you need to accelerate to pull out in front of them or face being boxed in until they pass.

 

[Shude]

off the top of my head yes

The car infront of you is doing 60 MPH its 500 yds away but, you're gaining on him quite rapidly, in your mirrors the queue of traffic is gaining on you, you need to accelerate to pull out in front of them or face being boxed in until they pass.

You indicate and change lane.