Fuel Consumption

Chong

Spurred on by tonight's TG episode.

Can someone tell me whats the best way to conserve fuel?

Last Friday , I decided to top my petrol up, and a mate of mine was in the car. He said why am I topping up, if I had half a tank.

I always leave mine drop to half a tank and then refill.

Is it better to let the tank drop right down to nearly empty and fill up when the tank is nearly empty?

Sandwich

No, dont think so.
The heavier the car the greater the quantity of fuel it will take to accelerate it. So dont fill up at all. Keep the tank almost empty all the time. Only add minimum fuel when you stop to do your next journey plus get you to the a petrol station.

What was TG saying ?

mickdw

It doesnt make sense to be carrying around all that petrol for nothing. I would let it reasonably low before topping up and seeing as you were already happy to stop every half tank for petrol, you could still do the same therefore saving yourself carrying a half tank of petrol extra all the time

Chong

mickdw wrote: »

It doesnt make sense to be carrying around all that petrol for nothing. I would let it reasonably low before topping up and seeing as you were already happy to stop every half tank for petrol, you could still do the same therefore saving yourself carrying a half tank of petrol extra all the time

Ok so I get ya.

Its something I got from my parents, they always kept their tanks topped up.

I am going to change though and not fill up as much in future.

Climate Expert

Car with greatest range?

Bmw 520D?

Ta me anseo

Keep your tank close to empty but only as long as the price of petrol is stagnant or going down. If the price is s going up, then fill up all the way so that you are getting as much petrol at the current price before the price changes again. You may have a slightly lower mpg as a result of being a little heavier but your cost per mile will minimised.

HashSlinging

Climate Expert wrote: »

Car with greatest range?

Bmw 520D?

I thought the merc E220 cdi was the best, according to Autocar mag.

Hal1

I keep her out of the red E-\---F <---like that .

old boy

I.M.O. its best if one tops up once a week when i start to put in 10 and 20 euro at the time i get less M.P.G.

Rowley Birkin QC

In all honesty I could not be arsed going to the petrol station as often as you guys seem to be doing in the name of saving a few quid.

Not worth it in my opinion. Any time I go to get fuel I fill it up to the brim.

fletch

Ditto, only fill up when I'm near empty and always brim it. Hate going to the petrol station so the less I have to do it the better.

RichyX

bigkev49 wrote: »

In all honesty I could not be arsed going to the petrol station as often as you guys seem to be doing in the name of saving a few quid.

Not worth it in my opinion. Any time I go to get fuel I fill it up to the brim.

Same as that.

Used to wait until my Ibiza had it's fuel light on to stick in 20€.
Easier and less time consuming to just fill it up each time.

kluivert

How to save fuel.

1. Drive at a consistent speed, not speed up slow down
2. 56mph is suspose to be the most econonical speed for a car.
3. Try and not brake, ie dont drive too close to the car in front, let your car slow down naturally.
4. Do not accelerate down hills.
5. Put on slow music, as fast music makes you drive more aggressively.
6. Press in your clutch about 500m before the junction, your saving 500m worth of fuel. Same principal as driving down hills.
7. Turn off all electrical items in the car accept the radio, uses very little power.
8. Reduce the weight of the car as much as you can.
9. Fill to the brim, and dont re-fill till the fuel warning light comes on, will give you the MPG average.
10. Ensure your tyres are inflated to the correct manufacturers specs.

Note: If you drive alot on Motorways, slightly increase the tyre pressure for better economy, WARNING, over inflating your tyres is danagerous, can cause a blow out, and reduce the handling capabilities of the car, e.g. try going around a corner at speed with over inflated tyres and see what happens.

Mr.David

kluivert wrote: »

How to save fuel.

1. Drive at a consistent speed, not speed up slow down
2. 56mph is suspose to be the most econonical speed for a car.
3. Try and not brake, ie dont drive too close to the car in front, let your car slow down naturally.
4. Do not accelerate down hills.
5. Put on slow music, as fast music makes you drive more aggressively.
6. Press in your clutch about 500m before the junction, your saving 500m worth of fuel. Same principal as driving down hills.
7. Turn off all electrical items in the car accept the radio, uses very little power.
8. Reduce the weight of the car as much as you can.
9. Fill to the brim, and dont re-fill till the fuel warning light comes on, will give you the MPG average.
10. Ensure your tyres are inflated to the correct manufacturers specs.

Note: If you drive alot on Motorways, slightly increase the tyre pressure for better economy, WARNING, over inflating your tyres is danagerous, can cause a blow out, and reduce the handling capabilities of the car, e.g. try going around a corner at speed with over inflated tyres and see what happens.

Agree with almost everything except:

2. Pretty sure that is only a myth, higher gear and lowest speed = greatest economy and will depend heavily on the car.

10. For greatest economy you can over inflate your tyres by about 10%. Downside is reduced grip/worse ride and faster tyre wear so on second thoughts dont bother

6. Dont clutch in, just let the car roll in gear as this uses much less fuel than when you clutch (in a modern car anyway)

Anan1

Mr.David wrote: »

6. Dont clutch in, just let the car roll in gear as this uses much less fuel than when you clutch (in a modern car anyway)

Won't this invoke engine braking?

C.D.

Mr.David wrote: »

2. Pretty sure that is only a myth, higher gear and lowest speed = greatest economy and will depend heavily on the car.

Higher speed --> the greater the drag co-efficient (air resistance). Thus it requires more force to maintain speed/accelerate. Also, this is very dependent on the car (i.e. what speed do you get at 2.5k RPM in fifth), so the "optimum" speed will vary with car and road conditions (wind, rain etc.)

Mr.David wrote: »

6. Dont clutch in, just let the car roll in gear as this uses much less fuel than when you clutch (in a modern car anyway)

Yup, if you clutch is not engaged your car is idling, if you are in gear and the throttle is closed (no fuel being burnt) you are being more fuel efficient.

nhughes100

Don't forget keep your oil well topped up especially in Diesels and use a good quality grade of oil, aside from that, low revs and high gears and get yourself a good diesel. Regular servicing helps too!

Rowley Birkin QC

kluivert wrote: »

How to save fuel.

1. Drive at a consistent speed, not speed up slow down.......


10. Ensure your tyres are inflated to the correct manufacturers specs.

Not braking is a bad habit to get into in fairness. They are there for a reason. If you are always expecting the car in front to slow at a gentle, consistent speed then a bad fright or worse is waiting for you.

Kluivert wrote:

8. Reduce the weight of the car as much as you can.

Also about saving weight, I have heard of people not carrying a spare wheel/jack/socket set etc. Where is the point of saving few quid on fuel if you have to call out a rescue vehicle to help you sort out something as basic as a puncture?!!

Kluivert wrote:

7. Turn off all electrical items in the car accept the radio, uses very little power

Make the drive more economical but more uncomfortable? No thanks.

Kluivert wrote:

5. Put on slow music, as fast music makes you drive more aggressively.

Lol.

Boskowski

kluivert wrote: »

7. Turn off all electrical items in the car accept the radio, uses very little power.

The alternator generates far more electricity than needed for all the stuff in a car. Plus some more to actually charge the battery. So you can play the music as loudly as you like. Anything that runs on the battery/alternator. Doesn't matter with regards to fuel consumption.

Air condition is different as it's not being run on the alternator.

pred racer

Mr.David wrote: »

6. Dont clutch in, just let the car roll in gear as this uses much less fuel than when you clutch (in a modern car anyway)

Dont clutch in, just let the car roll in gear In most modern cars this uses NO fuel.....

L1011

realcam wrote: »

The alternator generates far more electricity than needed for all the stuff in a car. Plus some more to actually charge the battery. So you can play the music as loudly as you like. Anything that runs on the battery/alternator. Doesn't matter with regards to fuel consumption.

Incorrect. The alternator puts a higher load on the engine the more electricity is being used. Sit in an idling car and turn on your full beams and listen to the engine note change noticeably.

Basic physics.

pred racer

MYOB wrote: »

Incorrect. The alternator puts a higher load on the engine the more electricity is being used. Sit in an idling car and turn on your full beams and listen to the engine note change noticeably.

Basic physics.

100% correct. Think of a generator, it idles fine and then, when you plug something in and use it you will hear it struggle for a second while it throttles up to take the new load.

Anan1

Mr.David wrote: »

Dont clutch in, just let the car roll in gear as this uses much less fuel than when you clutch (in a modern car anyway)

C.D. wrote: »

Yup, if you clutch is not engaged your car is idling, if you are in gear and the throttle is closed (no fuel being burnt) you are being more fuel efficient.

pred racer wrote: »

Dont clutch in, just let the car roll in gear In most modern cars this uses NO fuel.....

Lads, i'm lost here. If you take your foot off the accelerator in gear the car will decelerate far more quickly than if you were coasting in neutral. This is because car in gear + no throttle = engine braking. How can this possibly be more fuel-efficient than coasting?

granturismo

I'm fairly sure the advice below was given in a similar motor's thread. It's from an Australian or S African forum so temp v density advice mightn't be too relevant when the temp is fairly constant at 7C for most of today.

Letting the car's fuel tank almost empty - doesnt that increase the risk of any crud at the bottom being agitated and clogging the pump or worse?

• ONLY BUY or FILL UP YOUR CAR or BIKE IN THE EARLY MORNING WHEN THE GROUND TEMPERATURE IS STILL COLD.
• Remember that all service stations have their storage tanks buried below ground. The colder the ground, the denser the fuel, when it gets warmer petrol expands, so buying in the afternoon or in the evening.... your litre is not exactly a litre.
• In the petroleum business, the specific gravity and the temperature of the petrol, diesel and jet fuel, ethanol and other petroleum products play an important role. A ‘1’ degree rise in temperature is a big deal for this business. But the service stations do not have temperature compensation at the pumps.
• [WHEN YOU'RE FILLING UP, DO NOT SQUEEZE THE TRIGGER OF THE NOZZLE TO A FAST MODE. If you look, you will see that the trigger has three (3) stages: low, middle, and high. In slow mode, you should be pumping on low speed, thereby minimizing the vapors that are created, while you are pumping. All hoses at the pump have a vapor return. If you are pumping on the fast rate, some of the liquid that goes to your tank becomes vapor. Those vapors are being sucked up and back into the underground storage tank so you're getting less worth for your money.] – Currently Not applicable in India, as we don’t fill up ourselves but worth watching the man who fills up your vehicle.
• ONE OF THE MOST IMPORTANT TIPS IS TO FILL UP WHEN YOUR TANK IS HALF FULL. The reason for this is, the more fuel you have in your tank, the less air occupying its empty space. Petrol evaporates faster than you can imagine. Petroleum storage tanks have an internal floating roof. This roof serves as zero clearance between the petrol and the atmosphere, so it minimizes the evaporation. Unlike service stations, here where one of my friend works, every truck that they load is temperature compensated, so that every litre is actually the exact amount.
• ANOTHER REMINDER, IF THERE IS A FUEL TRUCK PUMPING INTO THE STORAGE TANKS, WHEN YOU STOP TO BUY, DO NOT FILL UP.Most likely the petrol/diesel is being stirred up as the fuel is being delivered, and you might pick up some of the dirt that normally settles on the bottom. Hope, this will help you get the maximum value for your money.

L1011

All of the those are untrue and debunked on this forum already.

Pumps correct for temperature
Vapour production rate doesn't change
Your petrol tank is a sealed system!
Pumps have filters

Boskowski

MYOB wrote: »

Incorrect. The alternator puts a higher load on the engine the more electricity is being used. Sit in an idling car and turn on your full beams and listen to the engine note change noticeably.

Basic physics.

Haha, what are u driving? A lawnmower? No, seriously are u takin' the piss or what?

cyborg

I can see the long queues forming as people slowly fill their car cent by cent to cut down on losses due to vapour... :D

Cookie_Monster

kluivert wrote: »

How to save fuel.

6. Press in your clutch about 500m before the junction, your saving 500m worth of fuel. Same principal as driving down hills.

How does this work, surely the engine is using fuel to idle in neutral rather than shutting the injectors down while not under load in gear?

L1011

realcam wrote: »

Haha, what are u driving? A lawnmower? No, seriously are u takin' the piss or what?

No.

I'm entirely serious. You, however, appear not to be, or at least your attempts to type like someone not old enough to drive suggest that.

Dades

realcam wrote: »

Haha, what are u driving? A lawnmower? No, seriously are u takin' the piss or what?

It's true - I see it all the time! (And my lawnmower is a 4.5 litre one... )

Cookie_Monster

Dades wrote: »

(And my lawnmower is a 4.5 litre one... )

Which bit, the grass box? :D:D