A way to use less petrol?

Pew_Pew_Pew_Lasers!

Magnets - wrong
Air filter - don't wash it. Replace it. Paper doesn't like getting wet.
Veg oil - not with a Lucas fuel pump
Tyres - DON'T OVER INFLATE TYRES !!!!!!
Oil additives - just use good oil in the first place, additives are worthless
Magnets - waste of money, no scientific evidence whatsoever, snake oil
Car insurance - you get what you pay for
Tyres - they don't require tracking. Wheels do.
Transmission additives - do not use. Stick to recommended gear oils for the gearbox, nothing else

Magnets. lol.

gowinm

Had not heard the magnets one....Try keeping your heater on full as warm air always rises thus making your car lighter! Try to get air on speed bumps as this dramatically reduces rolling resistance. Fill all tyres with helium and finally, knock out all that useless, heavy glass. I've found it to be just as clear if you do.

Try using your throttle about 25% max when accelerating, keeping revs no more than three thousand as you build speed. Generally cruising should be carried out as if there is an egg under your foot with an emphasis on trying to maintain a consistent safe speed. That said you can sacrifice some speed travelling uphill if you can gain it back in a moment accelerating downhill. Check your mirrors though - don't go annoying people behind!
Most engines I have driven are most effecient and perfectly happy operating around 1500rpm (as a minimum) on a flat surface but are far happier around 1750 to 2500 rpm overall.
Avoid braking for corners or hazards - learn to lift off your gas pedal early to adjust your speed using engine braking.
Leave a MINIMUM gap of 2 seconds from the vehicle in front. This will help you to see around the vehicle ahead better so you can better plan and anticipate when to lift off on your gas pedal- it is also safer of course!
Leave three to four car lengths in slow moving traffic on the same basis. People will pull out in front of you from side roads - go ahead make their day better and feel good about yourself too.
Traffic lights often have pressure sensors in the roads... don't keep up with the flow of traffic over these or move too slowly and the lights are gonna change on you!
Pedestrian crossings (these often have pressure sensors in the road on faster streches and sensors on the top of the light stack facing at you for slower limits. Regarding the ones with sensors on top of the light stack - usually the lights wont change all the while a car is in the area marked out with zig-zagged lines in either direction of traffic flow although be warned as I have seen some with very short zig-zag areas where these guidelines do not apply.
Pelican - have a given time for the pedestrain to cross the road, once this is up they beep and have flashing amber lights. You may proceed if the amber light is flashing and the person crossing has made it to the footpath. If the road is wide, the system will give the pedestrian longer to cross so back off. If it is an old lady on a zimmer frame, also back off early as she wont make it too the pavement on the other side quickly (or at all if you have magnets attached to your car!). If you can see its someone out for a jog and the crossing is narrow take an educated guess about when the lights will change in your favour.
Pelican - these are sensor based crossings identifiable by the green and red man combined on the box with the push button used by the pedestrian. They also have black or grey sensor boxes pointing down at the crossing area. Usually these are harder to predict when they will go green again but once the light sequence changes to red they stay that way until all pedestrians are away from the crossing area and pavement. Get to know how your local ones work and you can plan to avoid stop starting which kills your fuel effeciency!

Hope that helps save some fuel - sorry to waffle!!

Question: Assume fuel weighs 1kg a litre or 4.5kg per gallon. My car emits 178g of Co2 per KM and does 57km per gallon (officially), therefore it emits just over 10kg of carbons per gallon.... where do the extra carbons come from between the original weight of the fuel and the final emissions?

Pew_Pew_Pew_Lasers!

gowinm wrote: »

where do the extra carbons come from between the original weight of the fuel and the final emissions?

Fuel doesn't combust without oxygen.

sassybooboos

im training to be a driving instructor at the minute and its all about eco driving.

my instructor has said to me when changing gears block change as much as you can or think of it this way for every gear change you use an egg cup full of petrol.

i soon learnt how to block change,

thescouselander

gowinm wrote: »

Question: Assume fuel weighs 1kg a litre or 4.5kg per gallon. My car emits 178g of Co2 per KM and does 57km per gallon (officially), therefore it emits just over 10kg of carbons per gallon.... where do the extra carbons come from between the original weight of the fuel and the final emissions?

First of all, petrol weighs more like 700g per litre - diesel is a bit higher at around 800-900g per litre.

Secondly, your car will have emitted 10kg of CO2, not carbon. Since, there are 2 Oxygens to every one carbon in CO2 only a third of the mass of the emissions will be from carbon from the fuel. 2/3 of the mass will be comprised of oxygen which was drawn from the air that the engine sucked in.

So, assuming your car is a petrol model (this may be wrong) The actual weight of fuel in a gallon is about 3.2 kg.

Total mass of CO2 emisions is approx 10kg and 1/3 of that (the carbon eliment of from the fuel is 3.3 kg - (which is pretty close the weight of 1 gallon of petrol).

I've only been very approximate here so if you did the same calculation using more accurate numbers you should find the two values match up.

Cardelia

Carbon makes up 3/11 of the mass of CO2, so 10 kg of CO2 means 2.77 kg of carbon.

Carbon makes up about 84% of the mass of petrol, assuming it's just iso-octane and octane (i.e. without any additives) - the other 16% is hydrogen. The density of petrol is about 737 kg/m³, so converting to gallons and taking 84% of that gets you 2.84 kg of carbon per gallon of petrol.

thescouselander

Cardelia wrote: »

Carbon makes up 3/11 of the mass of CO2, so 10 kg of CO2 means 2.77 kg of carbon.

Carbon makes up about 84% of the mass of petrol, assuming it's just iso-octane and octane (i.e. without any additives) - the other 16% is hydrogen. The density of petrol is about 737 kg/m³, so converting to gallons and taking 84% of that gets you 2.84 kg of carbon per gallon of petrol.

Thats a good point, I forgot about the hydrogen.

LandyAndy

Cardelia wrote: »

Carbon makes up 3/11 of the mass of CO2, so 10 kg of CO2 means 2.77 kg of carbon.

Carbon makes up about 84% of the mass of petrol, assuming it's just iso-octane and octane (i.e. without any additives) - the other 16% is hydrogen. The density of petrol is about 737 kg/m³, so converting to gallons and taking 84% of that gets you 2.84 kg of carbon per gallon of petrol.

The question about where the extra weight comes from was in the Sunday Times last week. Even my thirteen year old knew this was the answer.:T

gowinm

thescouselander wrote: »

First of all, petrol weighs more like 700g per litre - diesel is a bit higher at around 800-900g per litre.

Secondly, your car will have emitted 10kg of CO2, not carbon. Since, there are 2 Oxygens to every one carbon in CO2 only a third of the mass of the emissions will be from carbon from the fuel. 2/3 of the mass will be comprised of oxygen which was drawn from the air that the engine sucked in.

So, assuming your car is a petrol model (this may be wrong) The actual weight of fuel in a gallon is about 3.2 kg.

Total mass of CO2 emisions is approx 10kg and 1/3 of that (the carbon eliment of from the fuel is 3.3 kg - (which is pretty close the weight of 1 gallon of petrol).

I've only been very approximate here so if you did the same calculation using more accurate numbers you should find the two values match up.

Thanks for your reply - & Cardelia too!

So is it the case that a larger capacity engine will always emit more CO2 regardless of its fuel effeciency due to the extra oxygen sucked through? And if this is the case do you know if adding a turbo or supercharger would increase the CO2 output as some of the more CO2 effecient engines are diesel turbo's. I may have got the wrong end of the stick completely so feel free to mock me if the question does not make sense. I might ask that 13 yr old to re-phrase it if thats the case....

cyclonebri1

fuzyfelt wrote: »

Hi all,
I've been wondering for a while if this works, and just doing some quick calcs in my head maybe somebody could tell me if my working's wrong...

If I only fill up my car 1/2 full of petrol each time, do I save 'cos the car's more efficient 'cos it's not carrying around the extra 1/2 tank of petrol?

Based on these figures:
1000 kg car,
40 litre tank capacity which is about 40 kg,
full tank every week, about £30.

I calculate ruffly:
20kg ( half a tank ) is 2% of the weight of the car, so uses 2% less petrol.
2% of £30 is 60p x 52 = £31.20 per year.

I'm sure there's some complex integrals and stuff that can be used, but is there anything wrong with the basic idea? Is this an easy way to save £31.20 per year? Anyone got more info so we can work it out accurately? Does BP not want us to know this?

Andy

Lots of good advice given, but to make by far the biggest savings simply drive slower and only drive when you have to. Of course to those that aren't that concerned about money, saving please ignore:j