Best Fuel Consumption - Cruise or Right Foot?

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Sat 20 Mar 2010 12:55
Best Fuel Consumption - Cruise or Right Foot? - fredthefifth

Lets assume that we are considering motorway type driving in free flow conditions.

Just wondering if anyone has mucked around with this or has the facts?

Edited by fredthefifth on 20/03/2010 at 12:55

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Sat 20 Mar 2010 14:35
Best Fuel Consumption - Cruise or Right Foot? - b308

I suspect that it depends on how "smooth" you are with your right foot, I have always been able to keep a constant speed without cruise, but looking around me i sometimes wonder if I'm in a minority... looking at the number of people who speed up and slow down anything from 60mph up to 80mph all the time!

When its quiet and free flowing then I keep cruise on, but if its messy like the M25 then I don't use it... technically I suppose not using it would be more efficient as you would let gradients slow you down or speed you up rather than using the throttle... but I'm guessing... no doubt someone will have a definitive answer!

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Sat 20 Mar 2010 21:34
Best Fuel Consumption - Cruise or Right Foot? - movilogo

The trick is to maintain a constant speed. Now you can achieve this either via cruise control or acceleration control.

Not all cars have CC but all cars have accelerators.

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Sat 20 Mar 2010 22:05
Best Fuel consumption - cruise or Right Foot? - Altea Ego

people who do low fuel consumption tests, trials and contests always have the cc off.

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Sat 20 Mar 2010 22:15
Best Fuel consumption - cruise or Right Foot? - b308

True... but most drivers can't drive anywhere near as well as they can... I suspect that for the average driver, who can't even keep a constant speed on the level, that cruise would be better!

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Sat 20 Mar 2010 22:58
Best Fuel consumption - cruise or Right Foot? - CGNorwich
The trick is to maintain a constant speed.

No the trick is to maintain a constant engine speed. Thus on an undulating road driving manually you will accelerate down hill and lose speed climbing. cc will maintain a constant road speed which is less economical.

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Sun 21 Mar 2010 06:11
best Fuel consumption - cruise or Right Foot? - Honestjohn
I support cG Norwich. cruise is fine on the flat, but as soon as you get to an incline (and there are some surprisingly long ones on UK motorways), maintaining speed gobbles fuel. conversely, when descending an incline, there is no fuel economy benefit in allowing the cruise control to hold the car back. The tests of the Insignia ecoFLeX and Mondeo ecOnetic were both done using cruise on the flat only, watching the instant consumption figure, though both tests also included the same fast cross country section, not driven in the most economical manner. both cars had real trouble maintaining 50 in 6th in cruise whenever there was a slight incline in the 50 limit, so needed 5th on those occasions.

HJ
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Sun 21 Mar 2010 09:01
best Fuel consumption - cruise or Right Foot? - Manatee

I'm fairly sure I beat the cruise control on the undulating a41 through the chilterns. a driver can back off a little earlier on the crests, and pick up a free of momentum on the downhills to reduce the fuel consumption on the climbs. This only amounts to modest speed variations but it seems to be worth a cople of mpg when I'm in ultimate economy mode (as I am at the moment, resenting the fuel price increases!)

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Mon 22 Mar 2010 08:06
best Fuel consumption - cruise or Right Foot? - Andy P

My auto diesel seems to be better with cc. Uphill it only does what's required to keep the speed constant and on downslopes it more or less coasts along. Watching the fuel consumption gauge i found gentle inclines that i never knew existed before - it was only when the gauge dropped that i noticed. it's also nice to watch it move to over 50mpg on the downslopes.

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Sun 21 Mar 2010 09:37
best Fuel consumption - cruise or Right Foot? - bathtub tom

>>No the trick is to maintain a constant engine speed

assuming you're in top gear, then the engine speed will be directly proportional to the road speed.

Please tell me how to maintain a constant engine speed whilst varying road speed?

I would have thought cc could have a 'fuzzy logic' built in to aid economy. I recall seeing a demonstration of this built into self steering gear on a motor launch. Without fuzzy logic the rudder was constantly swinging to maintain the set course, creating extra drag and increasing fuel consumption. With fuzzy logic switched on the course meandered more, but with reduced rudder movement, less fuel was used and the overall course remained the same. I assume the same principles could be applied to throttle operation on cc.

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Sun 21 Mar 2010 20:34
best Fuel consumption - cruise or Right Foot? - daveyjp

i've done 230 miles today. The first 20 or so was the 50 limit M4, all done on cruise. The X type did 53mpg over this stretch, the best i've ever seen and if i could have achieved more with the right foot it wouldn't have been as relaxing.

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Sun 21 Mar 2010 21:23
best Fuel consumption - cruise or Right Foot? - CGNorwich

Please tell me how to maintain a constant engine speed whilst varying road speed?

Just keep the engine revs constant. as you go up hill you will slow down. a you go down hill you will speed up. Not a particularly fun way to drive but it is the most economical.


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Sun 21 Mar 2010 21:50
best Fuel consumption - cruise or Right Foot? - Altea Ego

you've all missed the point. The trick is to keep a constant throttle opening. Movemtn of your right foot uses fuel.

so your revs drop and so does your speed on up hills, and the speed climbs and so do the revs on down hill, but the foot stays anchored in the same place.

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Sun 21 Mar 2010 23:02
best Fuel consumption - cruise or Right Foot? - CGNorwich

ae - you're absolutely right

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Mon 22 Mar 2010 07:35
best Fuel consumption - cruise or Right Foot? - hbosken

Lets assume that we are considering motorway type driving in free flow conditions.

Just wondering if anyone has mucked around with this or has the facts?

What's a motorway? and what's free flow when you find one?

Not much call for cruise control in Scotland - no quiet motorways (let's face it, we don't have many of them anyway!)

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