How to maximise fuel economy

BrianD3

Just as a followup to the fuel consumption thread I thought I'd start a thread for people to post tips on maximising/improving fuel economy. From the other thread, some drivers are getting significantly poorer MPG from their cars than I would have expected.

My No.1 tip is: leave a big gap between you and the car in front when driving on country roads. This will allow a far smoother and more economical driving style. You'll do less accelerating, braking and changing gear and will be conserving momentum much better.

I have a few other tips as well but will wait to hear what others have to say first.

colm_mcm

Build up your speed slowly

Don't go over 80kmph

CelticChick

I was watching an old Top Gear the other day were Jeremy Clarkson drove an audi from London to Edinburgh and back again on one tank of petrol. Audi said it was impossible. The car on average did 35 miles a gallon with normal driving and he needed it to do 44.
He was doing everything possible to reduce fuel consumption, even down to filling the tank early in the morning when it is cold because Petrol is more dense and so you get that little bit extra for your money. It was really interesting but impossible to drive like that normally. He wasn't using the back window heater, the air conditioning etc and he was even strategically accelerating on hills. He did manage it in the end but only just.

colm_mcm

yeah, and the funny thing was that using cruise control actually increases your fuel consumption!

CelticChick

Ye true, forgot he said that about the cruise control.

crosstownk

Everything you use in you car is powered by the fuel. For example, on most cars you can hear the engine note drop when you turn on the heated rear window. Have you any idea how many people drive with this on 24/7. only use A/C when you need it. Don't turn on unnessecary lights. If you've lots of ICE up loud it too will affect you consumption. Don't turn your heater on untill the engine gets warm otherwise the car stays in cold running mode for longer which drinks more juice. But the worst offender of all is the heavy right boot - drive easy and progressively because you may save the price of a pint of beer!

smarty

Heated seats are a killer on fuel economy, but I take the hit because I like having a warm ass!

crosstownk

Anything that uses electricity to heat is heavy on fuel. But in our climate comfort can be worth the cost...............

mondeoman

CelticChick wrote:

I was watching an old Top Gear the other day were Jeremy Clarkson drove an audi from London to Edinburgh and back again on one tank of petrol.




I saw that too but it was a 4.2 v8 DIESEL not petrol .lovely car btw:D

CJhaughey

Don't forget regular servicing INCLUDING checking tyre pressures, make sure that Sparkplugs are all good, and Airfilter is clean.
These make a big difference.

colm_mcm

Heated seats are actually good for fuel economy,

Researchers at the National Renewable ENergy Laboratry in Colorado have calcualted that twmperature controlled chairs could cut fuel bills by 1p per litre. Scientists say individual heating systems for seats are more efficent than air-con, which maintains the temperature of the entire cabin

crosstownk

CJhaughey wrote:

Don't forget regular servicing INCLUDING checking tyre pressures, make sure that Sparkplugs are all good, and Airfilter is clean.
These make a big difference.

Very true CJH. Low tyre pressure increases rolling resistance and increases consumption. Too high tyre pressure does the opposite but reduces grip which compromises safety. Poor or degraded engine oil reduces engine efficiency leading to increased fuel consumption. Also bear in mind that there is nothing to be gained by over-servicing a vehicle - all it will do is cost you more. Stick to the manufacturers recommended service interval and always use the specified oil.

CelticChick

mondeoman wrote:

I saw that too but it was a 4.2 v8 DIESEL not petrol .lovely car btw:D

Oops sorry, ye you're right it was diesel!

BrianD3

All good points. Also aerodynamics/drag should be considered. Extra drag is going to affect economy, by how much I don't know. Extra drag could be caused by
-roof racks
-bullbars
-big spoilers and air dams
-damage to the car's bodywork
-a filthy dirty car
-a car with loads of heavy stuff in the boot causing the nose to point up in the air and catch the air

On the last point, of course weight will affect things too. If there are unnecessary heavy items in the car they should be removed

colm_mcm

filthy dirty cars are now believed to aid fuel consumption, or so i read during the week

Moanin

2 questions;

1.How does a dirty car increase fuel consumption?

2.How does cruise control increase fuel consumption? I have cruise control in my car and use it all the times when driving on motor ways.Isnt it just the same as having your foot on the accelerator?

crosstownk

Dirt = weight...........?

CC applies the throttle at a predetermined rate and doesn't take into account your driving conditions. It also appiles and releases the throttle to maintain speed (some cars) rather than your constant application by foot. I wouldn't say the difference is much but every little bit helps.

Personally I don't see any need for CC in Ireland - too much traffic and not enough motorways.

colm_mcm

crosstownk wrote:

Dirt = weight...........?

CC applies the throttle at a predetermined rate and doesn't take into account your driving conditions. It also appiles and releases the throttle to maintain speed (some cars) rather than your constant application by foot. I wouldn't say the difference is much but every little bit helps.

Personally I don't see any need for CC in Ireland - too much traffic and not enough motorways.

Apparently the surface dirt creates aids fuel consumption.

Find cruise control handy if you don't want to exceed a speed limit.

crosstownk

colm_mcm wrote:

Apparently the surface dirt creates aids fuel consumption.

Find cruise control handy if you don't want to exceed a speed limit.

I'd like to know more on the dirt business...

CC handy for speed control - better than that audio warning stuff. Beep Beep Beep - smash dash!!!

colm_mcm

crosstownk wrote:

I'd like to know more on the dirt business...

I read it during the week, can't remember where! but apparently some complex surfaces aid aerodynamics - contrary to previous thinking (might be a load of arse, but worth a mention)

Another fuel saving trick is to only 1/2 or 1/4 fill the car with petrol, instead of carrying around a full tank

crosstownk

Gonna check into this dirty claim - I'll post any findings here. Sounds like a load of arse alright but you never know......................

colm_mcm

can't find anything on the net about it. think i read it at work, will have a look on monday!

BrianD3

Re: dirt. It makes sense that dirt would increase fuel consumption as the surface of the car would be rougher compared to a clean, waxed car. The more roughness, the more friction as the car passes through the air. This should make a very small difference to fuel consumption on a car (it might make a more significant difference on something faster such as a plane) Also, as already mentioned dirt = weight. A car with loads of wet muck clogged under the wheel arches will be several kgs heavier than a clean car.

It is hard to imagine that dirt would improve economy as colm seems to be saying. I woudl also like to see the article that this idea came from!

colm_mcm

Auto Express 7th March 2006:


"Don't bother polishing your car - it wastes fuel! Scientists have discovered that rough surfaces can be more aerodynamic than shiny ones by helping vehicles slip through the air more efficiently
If the bumps are the size and shape of tiny cylinders, they keep the air flowing around the car. "This goes against conventional thinking," said Swedish researcher Jens Fransson."

Litcagral

colm_mcm wrote:

Auto Express 7th March 2006:


"Don't bother polishing your car - it wastes fuel! Scientists have discovered that rough surfaces can be more aerodynamic than shiny ones by helping vehicles slip through the air more efficiently
If the bumps are the size and shape of tiny cylinders, they keep the air flowing around the car. "This goes against conventional thinking," said Swedish researcher Jens Fransson."

Why do they polish Formula 1 cars? They talk about saving one hundreths of a second!

colm_mcm

Formula1 cars are covered in sponsorship!

Alun

colm_mcm wrote:

Auto Express 7th March 2006:


"Don't bother polishing your car - it wastes fuel! Scientists have discovered that rough surfaces can be more aerodynamic than shiny ones by helping vehicles slip through the air more efficiently
If the bumps are the size and shape of tiny cylinders, they keep the air flowing around the car. "This goes against conventional thinking," said Swedish researcher Jens Fransson."

... and are the 'bumps' created by dirt on your car "the size and shape of tiny cylinders" ? Don't think so. Sounds like a bit of soundbite journalism to me. I can kind of imagine that a controlled, specific textured surface might produce such results, but not just a layer of grime.

crosstownk

Bit of a guess here but would air not get trapped in the small undulations created by the dirt making the surface smoother from an 'air' point of view? Would this aerodynamic beeifit be enough to compensate for the weight of the dirt?

Squirrel

Alun wrote:

... and are the 'bumps' created by dirt on your car "the size and shape of tiny cylinders" ? Don't think so. Sounds like a bit of soundbite journalism to me. I can kind of imagine that a controlled, specific textured surface might produce such results, but not just a layer of grime.

When the grime gets on the car when it's at speed the wind probably pushes it back, and would form a slight cylindrical shape. A rain-drop is shaped like it is because of wind resistance, so grime could work in the same way, and the air flows smoother sround it as a result

That's just a guess now

crosstownk

colm_mcm wrote:

Formula1 cars are covered in sponsorship!

Additionally, F1 cars rely on airflow across the bodywork to ensure correct downforce is applied. This is referenced to a clean, polished car in a wind tunnel.

Squirrel

Maybe send this to a physics/engineering forum perhaps?