Car Fuel Consumption Savings – Cutting Emissions
by matt @ 6:12 pm. Blogged under Science & Technology, Thinking
On weekdays I typically eat lunch in the car whilst listening to the radio. On London’s LBC at 1pm they have a show dedicated to improving your life (life coaches etc.), which also features the odd ‘green’ environmental tip. Last month one piece of advice was ‘Drive your car with the tank half full - saving fuel and money, whilst cutting emissions to reduce global warming’. I wondered how much of a difference this would really make, so I did a test of 40 litres of petrol versus 20 litres of petrol – discovering that my little 1.1 litre Peugeot will go an extra 40 miles (worth £5.00) on two separate fuel stops, instead of one big one.
Now firstly yes… the forty mile drive to and from work isn’t that exciting, proven by the fact I could even be bothered to do this fuel consumption experiment. As it’s the only journey I do each day I know the average speed of my car would have been pretty constant at all times, the result was:
350 miles on 40 litres of petrol (costing £38.30) - £0.109 per mile
195 miles on 20 litres of petrol (costing £19.40) - £0.099 per mile
Of course the last 20 litres of a 40 litre tank of fuel do go 195 miles at £0.099 per mile, which means the first 20 litres of a 40-litre tank go 155 miles at £0.125 per mile. So by driving on 40 litres of fuel the car goes 40 miles less distance at a cost of about £5.00 at the pump (40 x £0.125).
Clearly there is a sliding scale here; the first 5 litres of a 40-litre tank are far more expensive than the next five and so on as the car gets lighter. One could even say that a 10-litre tank of petrol was still more efficient, but somewhere one has to be practical with our busy lifestyles.
For my purposes, calculating that driving on a 20-litre tank once a week, instead of a 40-litre tank once a fortnight, saves me £2.50 a week – or £130.00 a year. Ok it’s not going to pay the mortgage off but it does mean I’ll burn 134 fewer litres of petrol – a reduction of about 335 kilos of CO2 per annum (assuming 1 litre petrol releases about 2.5 kilos of CO2). With around 34 million cars on Britain’s roads, everybody making an effort to drive a half-full tank (assuming they don’t already do so) could save as much as 11.39 million tonnes of CO2 per annum – impressive!
Technorati Tags: fuel consumption, petrol, fuel, environment, co2 emmissions, carbon dioxide, global warming, greenhouse gases, greenhouse effect, petrol economy, peugeot 206
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November 29th, 2007 at 7:46 am
HI Matt
I disagree with the values you used in your estimations.
The best you can get is 1% extra mileage. I will explain why:
Let’s say your car weight including yourself is 1000kg. Driving with a full tank will add an average of 10kg extra weight (the weight of fuel will go from 40kg to 0 kg => average of 20kg, or for double stops at the gas station from 20kg to 0kg =average of 10kg).
The difference is 10kg (to make it simple I used a density value of 1kg/litre for fuel. In reality is 0,7kg/litre meaning the additional weight is even less significant).
So you have an extra 10 kg, which is 1% from the total mass, which results in the best case with 1% mileage increase.
Going more frequently to the gas station will more likely increase the consumption depending how much you stay in line. Plus opening the gas tank more frequently will put more vapors into atmosphere. You will also add switch off and on the engine more often (3% increased rate, calculated 4 starts during a regular day, resulting 32 starts in 8 days, plus 1 start at the gas station, or 2 starts at a gas station, depending if you fill the tank once every 8 days, or once every 4 days, 1/33=0.03) This extra start up resulting in rich air/fuel mixture (the oxygen sensor will need to get to the operating temperature before it controls the mix)…plus wearing the engine (insufficient lubrication, etc) which can result in shorter life time, and all this put more pressure on environment.
There are better ways to improve mileage. Check tires pressure. Don’t carry unuseful stuff. Don’t accelerate to sudden. Don’t go more than 90km/h.
(Using AC has almost the same energy effect like keeping the windows down…increased air friction. Using the headlights during day time adds aprox 100 Watts…and if you have a 55KW engine, used at 15% its capacity (in normal driving) means you use a power of 8,25kW and lets say your generator has a 100% efficiency…you will 100 W to 8250W…which is less than 1,3%.)
Good luck!
Cristian
January 6th, 2008 at 11:38 pm
Hi Chistian,
I am currently learning to drive, when I do get my car and pass my test, I will not be using it much as parking where I work is absolutely despicable. I can get the bus and then walk less distance then I can park or I pay more in parking fees alone than the bus fare. If I do a long journey on a hot day which would be less environmentally damaging? To wind down the window or use the air conditioning?
February 16th, 2008 at 3:21 pm
Hi Everybody
Here are three fuel saving tips that, maybe, not everyone thinks of.
1. Think Shade
Park your car in the shade whenever possible. The same sun that is boiling up your steering wheel is also stealing fuel from your tank. It’s called evaporative emissions and it’s common in cars that are more than five years old.
Keeping your car in the shade also helps to keep it at the same temperature so you don’t have to fire up the air conditioning when you’re ready to leave. If you have a garage you can use, or an underground car park that’s an even better option.
2. Forget The Street Cred
It may look cool, but spoilers can spell disaster if you’re looking to conserve fuel. Spoilers may be marketed to give you that extra stability and handling, but according to most in-the-know they have virtually no aerodynamic benefit on most cars. In fact, spoilers can have a very negative impact on fuel conservation.
You may also want to rethink installing that 50 inch subwoofer in your car. Anything that makes your car heavier will make your fuel bill more expensive.
And finally, leave off the larger tyres. The larger the tyre, the more fuel it takes to accelerate and stop the car.
3. Keep Your Cruising To The Highways – Not The Byways
Cruise control can be very tempting. Especially when you have a stretch of nothing but straight road. And it can also be good for your wallet. If you’re able to maintain a steady speed for some time, using cruise control can improve your fuel consumption.
However, if you’re driving in hilly terrain, your fuel consumption will increase. Using cruise control causes your engine to speed up to maintain the preset speed. You’ll save much more fuel by using the gas pedal yourself.