Eco Driving

J

JStone

Ex. Club Member
Anyone got any tips for driving with out consuming vast amounts of petrol? I've heard rumours that letting your foot off the throttle completely to slow down (engine braking) consumes no petrol at all, any confirmation?

Also, driving in the highest gear possible helps, right?
 
Keep to lower revs, make sure your tyres have the correct pressure and even giving the car a service can improve the economy of the car!
 
justin

my lambda voltage drops to zero when i lift the throttle, so maybe the injectors close fully
but it ticks over if i coast, so it can,t be speed sensor controlled :confused:
 
coasting uses less fuel as this is idling but moving at the same time

engine braking uses more fuel as your reving up the engine.

Ryan.
 
frank said:
justin

my lambda voltage drops to zero when i lift the throttle, so maybe the injectors close fully
but it ticks over if i coast, so it can,t be speed sensor controlled :confused:
Click to expand...

Wont have any of that on a K10
 
around 56mph is the optimum speed. My 1.0l has done 65mpg at this speed on the motorway. I coast alot. I believe this is illegal - but if correctly applied can save you loads of money.

Driving in the highest gear possible will save you money IF you are very gentle with the throttle. 20mph in 4th gear is fine - but if you use loads of throtle to accelerate you will have wasted loads of fuel.

Try not to slow down, and if you have to, do it slowly.
 
richj said:
around 56mph is the optimum speed. My 1.0l has done 65mpg at this speed on the motorway. I coast alot. I believe this is illegal - but if correctly applied can save you loads of money.

Driving in the highest gear possible will save you money IF you are very gentle with the throttle. 20mph in 4th gear is fine - but if you use loads of throtle to accelerate you will have wasted loads of fuel.

Try not to slow down, and if you have to, do it slowly.
Click to expand...

coasting actually uses more fuel than leavimg it in gear and rolling as the engine has to keep the engine running were as if your in gear the cars momentum is helping turn the engine!
plus yes it is illegall as your not "in control of the vehicle" officially
plus youll find that driving slowly in a high gear also uses more fuel than being in the right gear for the road speed check out I.A.M. site it has written about this before, but the most fuel effective way to drive is to be smooth eg steady acceleration changing gear at the proper speeds not thrashing the engine or straining it running in too high a gear at low speads or up steep hills etc. and make sure your car is regullarly service to keep it running as economically as possible!
 
Accelarate appropriatly (long words with no spell check), maintain a steady speed, look far ahead and look for hazards, slow down smoothly and maintain speed where possible. If a junction is clear (and you must be 100%) then why stop? And if your on the motorway try and tuck in behind an unladen truck, it'll be doing the full 56/60 rather than full ones that may be slower up hills etc...
 
coasting actually uses more fuel than leavimg it in gear and rolling as the engine has to keep the engine running were as if your in gear the cars momentum is helping turn the engine!
Click to expand...
Not True! What has the cars momentum got to do with how much fuel is used?? Its the rpm and the amount the throttle is open that counts. I have rolled over 6miles out of gear. Are you telling me it would have been cheaper to make the engine do something other than tick over?
 
richj said:
Not True! What has the cars momentum got to do with how much fuel is used?? Its the rpm and the amount the throttle is open that counts. I have rolled over 6miles out of gear. Are you telling me it would have been cheaper to make the engine do something other than tick over?
Click to expand...

YES!

and where the beep would you find enough road un obstructed downhill to coast for 6miles! :suspect: do you live in scotland or something? youd be lucky to get a mile any where near me and i live in a hilly area! plus why the beep would you want to coast for 6 miles even if you could! :glare: youd be going so slow you would hardly be moving, and the engine would still be using fuel at a similar rate as if youd drove the 6 miles at 30 mph :doh:
 
coasting saves petrol surely ? because engine braking slows the car down (try pushing a car in gear :laugh: ) , if you coast you can lift the throttle a lot earlier at red lights or roundabouts, and downhill of coarse
 
Modern engines use no fuel if your rolling to a stop in gear (said so on Top Gear lol) the momentum saves the need for fuel to be injected as you are using momentum, you use a bit of fuel if your coasting as the engine is ticking over. The difference is neglegeable though if you have a lead foot.

And this wont apply to the k10 owner who posed the question as this also doesnt apply to carbs. :grinning:
 
Some good points there although surprised nobody said avoid braking!

Keep a good distance between you and the car in front and if he for instance stops you can slow down earlier by taking your foot off the pedal and he might get going again or might speed up again before you slow down too much or stop.

You only have to build up all that momentum again, which is costly with a small engine.
 
OBSERVATIONS TO SAVE FUEL

raise your vision UP higher (horison, over the trees, whats happening many cars infrot, lamposts, hdgerows, telegraph poles etc and keep moving betweendiferent distant and close spots consistently.....

you will build a bigger picture of what is changing and by how much....

the result will be less 'dabs' on the brakes....and less 'on and off' of the throttle.....

...smooth and subtle throttle control will pay you back in fuel consumption

GEARS TO SAVE FUEL

try to avoid revving the tits off the engine routinely
also try to avoid to HIGH of a gear.......
4th in a 30mph zome will use more fule than 3rd if you need 'response'
(squeezing the throttle in 4th will pump fuel but will not result in a decent change in speed.....but if in 3rd.....only a slight throttle adjustment will pick the speed up but without pumping fuel (carburettor prrgression enrichment)

MAINTENANCE TO SAVE FUEL:

good ignition, fueling (filters & settings), oil and the rest will zip you arround for less

:)
 
make like malcolm in the middle and become a god to a group of strong men... then have them pull your car (Y)
 
richj said:
Not True! What has the cars momentum got to do with how much fuel is used?? Its the rpm and the amount the throttle is open that counts. I have rolled over 6miles out of gear. Are you telling me it would have been cheaper to make the engine do something other than tick over?
Click to expand...

come on think about it bro
a lorry punches a huge hole in the air travelling at 55mph
when you slip stream the lorry the air is broken turbulance and is being dragged by the moving lorry!

Your wind resistance is greatly reduced doing this and WILL this give definately give you better MPG

i used to do it all the time in a micra.... when i was a skint student in expensive old royal kingston-
it used to #### off loads of HGV's doing 56mph for optimum MPG

a heavy cars momentum will carry on rolling for longer in coast whereas a small light car will not

if one does coast every 5mins be sure that you match the clutch revs with your engine speed-otherwise the clutch wear will out do any MPG savings

iam used to driving 2.0i16v's so driving a K11 is fuel saving enough for me at the moment lol
 
K-rusader said:
come on think about it bro
a lorry punches a huge hole in the air travelling at 55mph
when you slip stream the lorry the air is broken turbulance and is being dragged by the moving lorry!

Your wind resistance is greatly reduced doing this and WILL this give definately give you better MPG
Click to expand...
A) That's dangerous driving. If a lorry is doing 55mph and you're in his slip stream, you're going to go STRAIGHT into the back of him if he has to suddenly stop. Not only that, it reduces the chance the lorry driver can see you in his mirror.
B) Why did you quote him? The idea of coasting has nothing to do with being an idiot using aerodynamics to reduce drag.
 
Yeah I wondered that. I dont think anyone would disagree that reducing drag increases fuel economy. I've always wondered just how close you have to get behind a lorry for it to work.
 
richj said:
Yeah I wondered that. I dont think anyone would disagree that reducing drag increases fuel economy. I've always wondered just how close you have to get behind a lorry for it to work.
Click to expand...
They tested it on myth busters. About 18ft or something. I still wouldn't do it, that's not a safe distance.
 
From my days of having a motorbike i can say that you don't need to be that close to the lorry in order to get the slip stream. In winter i used to tuck in behind one (still 2seconds behind it ala highway code) and i was a hell of a lot warmer, and not thrashing my 125 as much to maintain speed!

Lol i guess me heel-toeing or blipping the throttle for every downshift doesn't help economy! (It DOES help my clutch though!)
 
tucking in or being fiarly close to lorrys may save fuel...but the lorry driver may not be able to see you...and your view of the road ahead will be rubbish at best.

....anyone ever experienced motormotorway traffic "suddenly" (that popular excuse for crap driving again) changing from 70mph to a crawl?......youre even less likely to see this developing from behind a truck...even if you're not tucked right in you view of the road will be a joke..
 
SammoHung said:
....anyone ever experienced motormotorway traffic "suddenly" (that popular excuse for crap driving again) changing from 70mph to a crawl?......youre even less likely to see this developing from behind a truck...even if you're not tucked right in you view of the road will be a joke..
Click to expand...

An the sudden thought after screaching to halt.............whys my seat damp! lol
 
agree i like to see whats going on in front of the car thats infront of me-to anticipate a sudden stand still from 80mph to zip=======X

i never said driving right up the ass of a lorry=slip streaming that is very dangerous and very stupid.

You can enjoy turbulant air from a high lorry from a close enough safe distance enough to react to a stand still from 55mph drop

Whense driving my K11 - i have had to make numerous emergency stops in the wet and this usually results in wheel skids to cars infront stopping dead

Best trick for me in the past has been to apply hard pressure in very quick bursts to stop the car from skidding.

it takes good skill and nerve-try it on a wet straight strip safe away from anyone to perfect it - it may save your life

when i totalled my first micra - i couldnt do this as i had 3m to stop dead at 40-50mph and she just slid down the ditch. I braced myself for the impact
the nurse said she could see the deep groove where the seat belt went across my chest circa 1.5 hour later!
 
Yes cadence breaking, what they used to teach for emergancy stops before most cars had ABS, you shouldn't need to use it in everyday driving. I don't see how you can get close enough to anything to get into a slip streaming position AND have two seconds gap?! (obviously significantly more if conditions are poor).

If your less than two seconds from my back bumper and I have to slam on you WILL hit me.
 
At the speeds lorrys go, 2 seconds isn't a massive gap. But there is turbulence for some distance back.
How beneficial it is i don't know.
 
I've been wondering about turbos and fuel economy. As an example, is it better to drive at 50mph (with only enough throttle to maintain speed on a flat):

a) in 5th gear 1.6k revs Turbo not spooled up
b) in 4th gear 2.2k revs Turbo spooled up.

Its got to be a. right?
 
ECUs add more fuel allong with the extra air that the turbo squeezes in.....but Im not sure how the distance / fuel graphs of turbo vs non turbo...or turrboed gears would look like ...interesting
 
whipit said:
What 50mph 2 second gap has a smaller braking distance than a 70mph 2 second gap. o_O
Click to expand...

Yes!
2 Seconds isn't a distance, its the length of time it takes you to get to some unmoving landmark that the lorry has just passed. At 70mph as you are going faster, to stay 2s behind you need to be physically much further back than at 55.
 

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