Decrease in fuel usage.

Feelgood

Hey chaps,

I did a wee experiment this week that might be worth trying for some of you. I don't know how the rest of you are fairing out though its costing me about €85 a week to fill my 320D and its crippling so I am obviously trying to get as many miles out of that as I can.

This week I toned down my driving a bit, I wasn't a speed monger or anything but would tend to sit at about 65mph on most journeys, so instead I dropped that down to about 55mph (70 on motorways).

Now I normally get in or around 520 - 530 miles from a full tank but this week I managed to squeeze out 613. Roughly an extra 80 miles from just dropping my speed down 5-10mph!. Well chuffed. Its means I am getting an extra trip to and from work out of a full tank.

Best thing is that it only really adds and extra 3-5 minutes onto a journey time too so might be worth trying out particularly for all ye diesel heads.

Next week I am going to try the same though am going to stop using air con etc to see will it be any benefit. Any chance of a couple of you lads trying it out too so that we can see the results?.

Prenderb

Hear hear, I tried that too , dropping about 5mph on the motorway and get another 20 miles out of my tank ( a petrol engine though ), mostly used on a short commute (10 miles) so the car isn't really warming up to it's best. Still, as you say, for a very small time sacrifice you can get significi

mukki

i noticed that too, i keep it around the 75-85km/h mark and it does indeed last longer, the slow coaches were right the whole time



i get a tank of bio diesel for about €55 and can do over 600 miles :cool:

some times i do over 50miles in a day

peasant

Speed isn't the only factor for fuel saving, but also how it is applied.

The engine is at its most efficient under full load (high gear, low revs, without labouring the engine) and on the overrun, when the car is being pushed under its own momentum or down a hill and you're off the gas, where the fuel supply is completely cut off.

The engine is at its least efficient on full throttle with high revs or when it's idling.

The "secret" to fuel efficient driving isn't to religiously stick to one set speed, but to drive fluently, use the momentum and engine braking, avoid sprints and hefty braking and keep idling to a minimum.

No point to tear awy from the traffic lights just to come to a screeching halt in front of the next ones.

No point in overtaking someone when the next obstacle is just in front.

But, also no point in holding everybody up, just so that you can save five cent at the filling station

Atomic Pineapple

as peasant says theres no need to go slower, if i need to save fuel i just keep the revs under say 3k while getting to that speed, the amount of fuel i save when i do this is very noticable

JHMEG

draffodx wrote: »

as peasant says theres no need to go slower,

I don't think he went so far as to say there's no need. The faster the speed the greater the wind resistance. You *will* save fuel by going slower. Motorways are a perfect place: no need to do 120 just cos you can. 90-100 and you'll get a lot further.

gyppo

+1 to all the above posts.

Another thing to look at is tyre pressure. Keep tyres inflated on the high side of manufacturers specs, and make sure there are no alignment/tracking issues. This keeps rolling resistance to a minimum, and lets you squeeze out another few yards...

peasant

JHMEG wrote: »

I don't think he went so far as to say there's no need. The faster the speed the greater the wind resistance. You *will* save fuel by going slower. Motorways are a perfect place: no need to do 120 just cos you can. 90-100 and you'll get a lot further.

correct ...just don't dawdle on single carriageways.

I've actually sped up on some stretches of my daily commute to save fuel

I drive the same bendy, hilly country road to work every day and I've now got it worked out to a tee where I need to gather momentum and where I can just let it roll and still make good progress while saving on fuel (and on unnecessary acceleration after unnecessary slowing down)

This also involves not slowing down before a particular bend and carrying the momentum through instead.

Feelgood

peasant wrote: »

The engine is at its least efficient on full throttle with high revs or when it's idling.

What do you mean by "idling" peasant??

peasant

Feelgood wrote: »

What do you mean by "idling" peasant??

when the engine is running and the car is not moving ...that's idling

Hard to avoid in heavy traffic, but it helps to keep a bigger gap to the car in front and look ahead to see what the traffic is doing ...that way you may be able to keep moving (albeit slowly) instead of having to come to a halt, idle and then accelerate again.

Atomic Pineapple

JHMEG wrote: »

I don't think he went so far as to say there's no need. The faster the speed the greater the wind resistance. You *will* save fuel by going slower. Motorways are a perfect place: no need to do 120 just cos you can. 90-100 and you'll get a lot further.

true, i meant you dont have to go slower to save fuel

Feelgood

peasant wrote: »

when the engine is running and the car is not moving ...that's idling

Hard to avoid in heavy traffic, but it helps to keep a bigger gap to the car in front and look ahead to see what the traffic is doing ...that way you may be able to keep moving (albeit slowly) instead of having to come to a halt, idle and then accelerate again.

Understood, didn't know they had a text book name for that!. hehe...

JHMEG

peasant wrote: »

correct ...just don't dawdle on single carriageways.

Which all have a maximum speed limit of at most 100 anyway. You will save fuel, and the possibility of points by staying under the limit, even when the road is empty and the temptation is there to nudge the speed up a bit.

spank_inferno

tried it last week knowing I would have a few mins to spare on commute time.
Averaged 47Mpg compared to my usual 38mpg (on a 1.4ltr fabia)
Easier to do now though as the traffic is noticibly lighter with the schools off.

Max_Damage

Just to note, they say driving at 55mph is the most economical speed to drive at.

wittymoniker

thought i agreed with all the above until i changed the car. was in a flat 6 and did best MPG at about 90 - 100kph. have a v8 now and going an extra 10 - 20kph (when able to sustain) gives a better return. different engines with different power curves i guess.

peasant

wittymoniker wrote: »

thought i agreed with all the above until i changed the car. was in a flat 6 and did best MPG at about 90 - 100kph. have a v8 now and going an extra 10 - 20kph (when able to sustain) gives a better return. different engines with different power curves i guess.

Different gearing would be my guess

snowman707

Unused roof racks, open windows,flags supporting your local gaa club, & unneceessary luggage all put a drag & affect fuel useage as does the air conditioning (big time) , also any item that puts a pull on the alternator.

craichoe

50 - 55 mpg Driving on roads in Holland,

18-22mpg driving on Roads in Germany .. Autobahn sucks that way.

Anyways i've started driving at 120 on the Autobahn, the crippling fuel usage is just not worth it at the end of the day. Over the course of an hour i could see the Fuel gauge slowly moving down !

It BeeMee

Another handy thing to do is use the Onboard Computer.
I always leave the OBC at "current consumption", it helps keep the foot lighter.

Try this: keep at a constant speed, say the fabled 55mph, and watch your consumption.
Push down ever so slightly on the accelerator: your consumption increases BUT there is no discernible change in speed.


Unfortunately I never do this any more cos I'm too fond of my cruise control....

Ice_Box

I changed my driving style a bit and my mpg went from 41mpg to 51mpg. Just got 691 miles from a single tank. €87 to refill. 2003 Audi A4 saloon 1.9tdi 130bhp.

Henry Ford III

Max_Damage wrote: »

Just to note, they say driving at 55mph is the most economical speed to drive at.

They say a lot of wrong things.

In various maximum economy runs, much lower speeds than that give greatest mpg.

55mph may well be the best compromise for journey times etc.

Feelgood

Right chaps,

Am a bit stumped to be honest. Filled the car and didn't use any air con for the last week or so. Drove exactly the same way as I did the week before, actually on exactly the same routes with around the same traffic or idling though only pulled 609 miles out of a full tank this week?

What gives??. Is it safe to say that Air Con has a very minimal effect on fuel usage then?. I thought I would actually pull an extra 20-30 miles out of a tank without air con on?.

craichoe

Its constant accelerating and braking that uses fuel. Try to speed up and slow down as little as possible.

mcwhirter

My rover 75 diesel gets about 600 miles out of a tank but when on a motorway checking the onboard computer if I stay under 60 mph I can get almost 700 miles. Thats about 7-10 mpg more.
If i take it beyond 70 mph then it can drop well below 550 miles.
So savings can be made but its a bit boring though driving like this, every so often I have to have a blast dowen the road

Ferris

Most cars with cruise control will use more when its on. I think its because the cc keeps on accelerating and decelerating to keep the car bang on a certain speed (not too sure about that!).

If anyone remembers that top gear where Clarkson drove from London to Edinborough and back in an Audi A8 4L diesel on a single tank. He put on the cc and the MPG dropped significantly.

L1011

Average mpg for my 20 mile drive in/out of work: 31mpg
mpg for a drive to/from Northern Ireland where I was rather a naughty boy along the way: 40mpg

In my car, warm engine seems to have more of an impact than speed.

HashSlinging

Coasting down hills in neutral rules. just find some hills eh.

tuxy

HashSlinging wrote: »

Coasting down hills in neutral rules. just find some hills eh.

Not the brightest are you?

Coasting is dangerous and you use less fuel by keeping it in gear while not pressing the accelerator pedal.

RobAMerc

Jaysus lads this is one depressing thread.

Do you know if you walk you don't use any fuel at all :rolleyes:

Anyway: The one thing we are blessed with in Ireland is relatively cheap fuel, so get out there and enjoy it while you can ! Remember you'd be paying 30c per litre more in some European countries !

alias no.9

HashSlinging wrote: »

Coasting down hills in neutral rules. just find some hills eh.

Coasting in neutral going down hills uses more fuel than having the car in gear with your foot off the accelerator. When your coasting, the fuel does all the work to turn the engine over, when you're in gear, the momentum of the car keeps the wheels turning which keeps the engine turning over while burning much less fuel than at idle.