By Daniel McCoey
With the price of regular unleaded topping $1.60 in Australia this week, protests breaking out across Europe at the price of fuel and an emergency oil summit being organized by a bunch of disgruntled nations, it seemed appropriate to look at ways you can stretch your fuel dollar further. Of course you could buy a hybrid but for us enthusiasts that would be a little like giving up on life, so lets look at how you might save a few dollars.
The first tip when refueling is to make sure you do it only in the dead of morning when it’s still cold, the colder the outside temperature the better. Most service stations have their storage tanks underground and the temperature of the fuel you buy will make a difference. The colder the ground, the colder the tank. The colder the tank the denser the fuel. Liquids expand as they warm and it is no different with petrol and diesel. A litre of fuel bought in the cool of the morning is denser than a litre of the same fuel purchased in the warmer afternoon. Simply put, filling up early in the morning means you are getting the best bang for your bowser buck.
Oil companies know all about the effect of temperature on fuel. When supplying their retailers they take into consideration the specific gravity and temperature of the fuel held in bulk storage to ensure that they supply their retailers with a real litre of fuel. They do not employ the same tactics at the pump though, where there is no temperature compensation and a litre is not necessarily a litre.
Another tip when filling up is – don’t rush. Most bowsers have the ability to ‘click in’ to a high flow rate but that doesn’t mean you have to use it. If you have the time then slowing down the fill rate minimizes the vapors that are created from the fuel being pumped. All hoses at the bowser have a vapour return for safety and those vapours are not returned to your tank despite the fact that you are about to pay for them. It’s a little like opening a bottle of Coke and pouring a glass quickly, you end up having to wait for the gas and bubbles to subside before you can return to filling your glass. Filling your tank quickly results a similar build up of vapour that either heads for the atmosphere (you can usually see the vapour itself distorting and refracting light around the filler) or returns to the storage tank via the vapour return.
It is common knowledge now that there are fuel price cycles each week and it pays to watch when Petrol stations in your area raise and lower their prices. Generally the best days to buy are at the start of the week with prices generally being bumped up from mid week onwards and then slowly working their way down again by the end of the weekend.
Fuel loss through evaporation can also be reduced by constantly keeping your cars fuel tank at least half full, although it may not be terribly convenient at times. Not only do Petroleum companies monitor and regulate the temperature of their fuel supplies, they also monitor the specific gravity of the fuel being held in storage tanks. Their storage tanks are equipped with an internal ‘floating roof’ that ensures there is zero clearance between the fuel and the atmosphere minimizing evaporation losses through exposure to the atmosphere. Maintaining half a tank of fuel in your car acts in a similar way to the storage tanks ‘floating roof’.
If Oil companies have processes in place to reduce losses from temperature differences and evaporation then you can bet there is a significant dollar it. It also means that there is potential for you to ensure that each dollar spent at the bowser buys you a full dollars worth of fuel.
Using some or all of these tactics will save you some money in the long-run, it won’t be enough for a down-payment on that silver GT3 you’ve been admiring but when fuel hits $2.00 a litre (as is being predicted) a few bucks saved at the bowser has to be a good thing.
Happy and safe motoring.
[Old bowser image source: Jalopnik]
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Very impressive. Especially about the expansion at temperature.
About the evaporation in your tank, while we’re on the same wavelength of maximising fuel economy, wouldn’t you be carrying around extra fuel that you’re not using whilst you’ve got a tank more than half full?
I think also removing all items from the car that you don’t need (from the boot and back seat) will help a great deal, putting on some chilled music so you drive more smoothly (so not the Prodigy’s Fat of the Land then) and as much as I like driving with the window down, putting the blower on instead on motorways (with no A/C if you can help it) to reduce drag.
Maybe we should also make sure our cars are nicely waxed at all times too, to minimise drag coefficient!
May I also suggest that another way to improve fuel efficiency is to remove any: No Fear; Frangipanni or Baby On Board Stickers from your car.
Godspeed - I’m going to wax my car this weekend - brilliant idea!
You are dead right about carrying extra weight.
I think the biggest fuel saving gains are to be had by simply adjusting your attitude behind the wheel.
I’ve become a bit of ‘cruiser’ these days and you certainly get more kays out of a tank, its not as much fun but you are more relaxed when you arrive at your destination.
Although I have been known to drive a car that has been on a diet, basically the removal of non-essential items like roof lining, sound deadening, spare wheel, rear seats, passenger seat, carpet, stereo and speakers, air conditioning and other items deemed as ‘luxury’.
I can assure you that although the vehicle in question was lighter, the way in which that particular car driven in no uncertain terms proved to be thirsty.
Maybe the track is not the best example of frugal behavior from a motor vehicle…
Old as the internet, and just as trustworthy.
http://www.snopes.com/inboxer/household/gastips.asp
I bet you forward those “forward this email and Bill Gates will donate another $10 to some charity” emails too…
wheelnut - OT but yes how those frangipani stickers suck dogs’. And I usually find drivers’ with the baby on board stickers on their cars have some of the worst self-righteous and self-important driving behaviour…
My advice for saving fuel: don’t commute if you can avoid it. Nothing kills economy like sitting bumper-to-bumper with the engine idling.
I’d rather burn my fuel doing something fun, so it’s public transport for me.
I can’t stand public transport. All it does is clog up the roads.
Personally I’ve avoided those Bill Gates emails, but I am waiting for $5,000,000 from Nigeria. You wouldn’t beleive it if I told you - but I will anyway. I got this email last week and all they wanted were my bank account details. The poor bugger had to get his families money out of the country and was prepared to pay me $5mill if I provided the account.
Soon the cost of petrol will matter little for me…
I think you’re onto something there Steane
Yeah I can’t stand public transport either. The story for the Government is the same - provide a viable alternative to driving our cars and we will use it. Provide a service that is almost always late, unclean, poorly designed (having to change trains like three times or use a ridiculous number of combinations of train / bus / ferry) and over priced, and is there any wonder there are so many people still using their cars. At least it’s warm, clean, you can turn the music up real loud and no one looks at you funny if you’re not wearing any pants
I too avoid the Bill Gates emails, and I’ve always been amazed of Nigerian Loyalty and the poor grammar they display when sending you an email saying they will be depositing $13,000,000 into my bank account.
Still waiting for the 13 mill of course…
Tony is right though; there are other ‘better’ ways to save money at the bowser. Routinely checking Tyre pressures, buying Petrol on the ‘cheaper’ days, removal of items such as roof racks that cause more drag, and keeping your car running at its absolute best are the prime (if not elementary) ways in which to keep fuel consumption down.
However, the suggestions above also help in saving money, albeit in very small percentages. None of those avenues have been disproved, but have been questioned on exactly how much they might save you.
As I said, it won’t help you buy that GT3 you;ve always wnated, or pay off your mortgage any quicker, but it may mean getting a few extra km’s out of a tank of fuel and that can’t be all that bad can it?
Ive become the yoda of not stopping at a set of traffic lights.
mmm, much fuel I use just to stop I will.
In this case “the force” is momentum
Not wearing any pants will also save weight Godspeed. Thats a win win situation in my book.
The problem with the roads is that the Govt build roads to try and deal with a population of 1m whne the current population is 4m instead of building roads to deal with 6-8m whilst the population is still 4m..
Therefore they are forced to enter into contracts with various construction comapnies to build new toll roads which means motorists end up paying for the govt incompetence and short-sightedness as well as causes delays whilst the road is under construction
The government says its to imporve traffic flow but all that really happens is that it relocates the “black spots” as more traffic converges in a different area than before
In the US during the 30-40s there were apparently some Highway Patrol cars with pneumatic jaws mounted to the front of them.
These jaws were designed to hook on to the back of the car that the cops were chasing inorder to catch those who were boot-legging [transporting alcohol across interstate borders] when they locke on to the car the cops would just hit the brakes
You could then apply the same idea in todays world
mount a set of jaws to the front of your car then when you get close enought to the car infront of you push the button so they lock on to the car infront then turn of your cars engine and put it in neutral and let their car pull you along the motorway
I think you are drawing a very long bow with the fuel temperature suggestion.
The temperature below ground is fairly constant and varies very little throughout the day. In fact as depth increases and from about 10 metres the Earth’s temperature is constant and close to the annual average air temperature.
So during winter - the air temperature is going to be much lower than the ground temp so the time of day you fill up is largely irrelevant.
Credability of this article is sadly lacking.
1. Air temperature has almost nill affect on the temperature of fuel delivered, a tank of fuel bought after a 5 day cold spell won’t get you any further than atank of fuel bought after a week of 35+ degrees.
2. Most modern cars have closed loop fuel systems, that don’t lose vapours to atmosphere, so no evaporation from your tank.
3. The reason bulk storage tanks have floating roofs is to avoid vapour traps, which are an explosion hazard.
Day of the week, not time of day is far more important, as is brand/blend/type of fuel. Do some tests and find what works best for your car & driving pattern. I avoid Shell as it gives me up to 50km less per tank (700 vs 650 km). I find E10 (ethanol blend) works fine in the city but poor on highways. Conversly Premium will add plenty to the distance possible on the highway, but is a waste of money for metro commuting.
Also beware any new car that “recommends” ULP but states max power figures based on a higher actane fuel (Holden V8 anyone), as using standard ULP will also affect economy as well as performance.
i dont know about full tank of fuel can kill evaporation, but it can be a bonus to all FWD cars as better front-rear weight distribution.
however, is it worth it carry the extra weight around 24-7?
I would also suggest visiting the abolutions before you drive anywhere. That extra half kilo of waste product can have an incredible dent of you fuel consumption. Another benefit of this being in the event of an accident one will not have to change ones underware as well.
Seriously I stop the engine at lights if i’m gonna be stationary for a time. Most engines will use about 0.2 to 0.3 litres per hour idling. I roughly worked out that I can travel an extra 50km/tank by doing this. Diesel are better for this as they do not “choke” to start when cold.