Is Cruise Control Economical?

DavidS

Active Member
Oct 17, 2012
119
0
Hello again folks,

As above, is Cruise Control the most economical way to drive on the motorway?

The reason i ask...Due to work i travel between Oxford & Scotland regularly. This journey is almost bang on 420miles, almost all motorway driving. When driving to Oxford yesterday i couldn't return more than 45mpg in my FR PD170.

The car has recently had injector recall and DPF Differential Pressure Sensor changed, surely it should be returning better MPG on long journeys??

P.S. I tried -
1 hour @ 70mph
1 hour @ 75mph
1 hour @ 80mph
None of the above returned more than 44.5 mpg using Cruise Control.

Any help/advice/tips would be great!

Thanks.
 

Ashworth

Active Member
Feb 2, 2010
152
0
Nottinghamshire
I travel from Nottingham to Scotland 2 or 3 times a year and setting the cruise control at 70 mph I get 54 mpg in my FR but it is the FL model with the CR engine. However I did used to get about 51 - 52 mpg when I previously had the PD model.
 

cupra_ahhh

Active Member
Nov 4, 2008
1,203
11
Tonbridge, Kent
I've found that in my fl Cupra, using cruise control does not improve fuel consumption, it really uses a lot more, almost like having you're air con on the whole time. I was travelling to and from Essex for a few months, so about 80 mile round trip, and was testing at 60 & 70 mph, made no difference. When I turned it off and drove without it, it was getting a lot more mpg. I was only using the "Range" function on the trip computer. My cars not even done 14k miles yet, so maybe that's a contributing factor.
 
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TimSawf

Active Member
Jun 26, 2011
865
3
South Manchester
This topic has been discussed before and there was a lot of differing opinion on it. My own opinion is that it isn't. Cruise Control will maintain the speed regardless of the terrain so it will accelerate uphill which is very bad for MPG. To get the best MPG, it's best not to accelerate more uphill to maintain the speed but to let the speed drop on inclines, then regain the speed on downhill sections or accelerate slowly on the flat.
 

AndyG_TSi

Active Member
Nov 1, 2011
1,174
6
East Manchester
Cruise control IS the most economical way to drive on the motorway.
Yes, it will ease off the power going downhill but use a bit more going uphill , but the KEY is doing 60mph for the best mpg return.

I'n my 1.4Tsi, I've done a round trip of Manchester - Edinburgh-Manchester on 1 tank of petrol. The maximum mag return on that run doing 60 on cruise was 56.4mpg from a petrol!!.

M60/M61/M6/A74M/A702 was the route
 
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DavidS

Active Member
Oct 17, 2012
119
0
Thanks for info folks.

But, surely i should be seeing more than 44.5 mpg at 70mph? I have to say i am disappointed in the lack of economy from my FR generally.

Would like to know what mpg other PD170 drivers are getting?

Also, do you all run on V-Power Diesel? As i am currenly using Shell Fuel Save Diesel.

Thanks again.
 

S3 AKR

livin' the dream!!!
Jun 30, 2004
1,453
1
Colchester, Essex
Mine is only doing about 41 mpg at 90 mph on motorway. Getting about 44mpg at 80mph on motorway, and an overall average of about 42mpg around town. Cruise makes little difference either way. The car has only done about 2.5k miles so far. My old PD150 that was modified and played with was about 5 mpg better. I am hoping that it improves a little as the engine loosens up.
 

DavidS

Active Member
Oct 17, 2012
119
0
Mine is only doing about 41 mpg at 90 mph on motorway. Getting about 44mpg at 80mph on motorway, and an overall average of about 42mpg around town. Cruise makes little difference either way. The car has only done about 2.5k miles so far. My old PD150 that was modified and played with was about 5 mpg better. I am hoping that it improves a little as the engine loosens up.

I'm on 54k at the moment so think its fairly loose at the moment. My old PD130 Golf was returning 50+ mpg with ease running standard map (and its cheaper on road tax), overall this 170 lump is not winning me over! Haha.
 

Crazy_Carl

Active Member
Sep 14, 2012
61
0
I drive from leicester to nottingham prob 3-4 times a week and is about 35 miles near enough all off it is motorway and i do about 70mph all the way and always return about 45mpg. i have found if i do 60mph on the motorway on cruise and driving like a gramps off the motorway i can get 47-48mpg .
 

S3 AKR

livin' the dream!!!
Jun 30, 2004
1,453
1
Colchester, Essex
I'm on 54k at the moment so think its fairly loose at the moment. My old PD130 Golf was returning 50+ mpg with ease running standard map (and its cheaper on road tax), overall this 170 lump is not winning me over! Haha.

I only got a diesel this time because I was insisting we had a Supercopa. After 21mpg in the 4.0, V8 M3 we had before, it is a huge improvement even if not as much as I thought it would be. Looking forward to getting it mapped in the not too distant future.
 

Noel<>leoN

Active Member
Oct 5, 2007
56
0
At motorway speeds the main work being done is balancing wind resistance. That scales exponentially, so the faster you go, the more fuel you'll use per mile. The best way I've seen it exalained is that although you're having to move the same car-shaped amount of air out of the way each mile, the faster you're going the faster it's getting chucked up in the air/out to the side. Moving the same amount of air out of the way but faster means your engine is doing more work and so using more fuel.

As people have said above, as a general rule of thumb the lower your speed the better your fuel economy. You have to make a personal choice balancing wasting your life on the road and pain at the pumps :)

Cruise control should use as much fuel as if you manually kept the car going at the exact same speed all the time. Realistically, you're always going to drift up and down a bit if you're controlling speed yourself (I find the cruise control is very good at maintaining the exact speed). Because of that exponential biz I mentioned earlier, it'll use up more fuel to go the same distance if you travelled half the time at 70 and half at 80 than if you just used cruise control to stay at 75 the whole time.

So, to cut a long story...long.... ;) I say decide how slowly you can stand driving such a long distance and then use cruise control to maintain that.

Usual caveats about speed limits/driving conditions etc always apply :)
 

S3 AKR

livin' the dream!!!
Jun 30, 2004
1,453
1
Colchester, Essex
Also are you trusting what the trip computer tells you your MPG is? Because its generally known there not accurate

I don't agree with you entirely on that one fella. The readings for the trip computer are read directly from the injector cycles and therefore pretty accurate. In the past 10 years or so these things have really come on well as fuelling has become more and more precise to meet emissions requirements. I would imagine the margin of error is basically the same as the odometer as that is the weakest link in terms of accuracy.
 

Nath.

The Gentlemans Express
Jan 1, 2006
8,620
16
EASTLEIGH, HAMPSHIRE
I don't think cruise control is any better or any worse than driving manually but it sure as hell saves on speeding tickets, sure as hell saves ankle pain from holding it still for ages and sure as hell makes for a less stressful drive.

people fly past me and I think "so what mate, you're foot is flat down and mine isn't even on the gas pedal"

Cruse control every time.
 

andycupra

status subject to change
your going too fast for great mpg figures.

there is no real definative answer as to whether cruise is good for mpg as it depends how good/disciplined driver you are.
Typically cruise is very good at being disciplined; as a result it often gives good mpg figures if you were for example to set it to 70mph and do an hours drive as it will make sure you only do 70. Someone driving manually however may fluctuate the speed a fair bit and many people would often go faster than 70mph.
However, cruise control is reactionary and a human has a massive advantage is being able to adapt and predict.
For example, if the route has alot of hills, uphill and downhill sections the cruise may go from no throttle to lots of throttle trying to maintain an exact speed which is inefficient. Whereas what you really want to do is allow some gain of speed on downhill sections and as a result be able to loose some speed or acvoid increasing throttle on the uphill sections which can be more efficient.

In theory, a drive that is discimplined and understands what efficient driving is and impliments it should beat cruise control. But the reality is most people are simply not as efficient or as good at driving as they think, and on a motorway cruise would be for most people an efficient way to drive.

There are some general misconseptions regards efficient driving, - just maintaining a constant speed is not everything, it helps yes but anticipation is the key.
 
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andycupra

status subject to change
I've found that in my fl Cupra, using cruise control does not improve fuel consumption, it really uses a lot more, almost like having you're air con on the whole time. I was travelling to and from Essex for a few months, so about 80 mile round trip, and was testing at 60 & 70 mph, made no difference. When I turned it off and drove without it, it was getting a lot more mpg. I was only using the "Range" function on the trip computer. My cars not even done 14k miles yet, so maybe that's a contributing factor.

the range function is based on a period of recent driving. so if you put the cruise on it wont instantly give you the new mpg/ranbge figure. instead after a period of time when you have some history of recently achieved mpg figures then the range will be updated.

Cruise control, on a flat straight road and with no other influences will give the same mpg figures at a set speed than someone maintaining the same speed manually.
The differences is cruise is reactionary, a person is pro-active (or should be)
 
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