The best way to spend less on fuel is to not use the car, of course. That's always my first option. We're a one car family and my husband uses the car for work so it is going during the day. That said, we also live in a large urban area, so for me public transport is plentiful and relatively painless to use.
Even so, once you have kids, you quickly find you really do need to have a car. And it needs to be a four door at least, as we quickly found out having to sadly and reluctantly trade in our lovely Mini Clubman for a Ford Focus.
So, how can you eke out that petrol? How can you make every penny spent on fuel go as far as possible? As always I turned to the internet and the collective wisdom of our PlayPennies parents to find out.
Sandy, mum to two boys, is probably typical of most of us. "All I really know about conserving fuel is that the correct tyre pressure makes a difference." She then thought for a moment before adding "I should probably check the tyres on our car then."
That's one problem right there. We all KNOW what we should do but we don't always actually do it.
Is it a myth, or a truth, that tyre pressure can make a difference to how much petrol you use? The RAC says that it is true. Check your tyre pressure regularly, and "you can improve fuel consumption - by up to 2%." The better reason to do it though is because it is safer. The organisation points out that poorly-inflated tyres cause the deaths of dozens of people each year.
Reducing your speed to save petrol is a tip that's often bandied about and I did wonder how true it really was. According to the Department for Transport, you'll save about 10% in fuel use if you drive at 70mph rather than 80mph.
The optimum is really around 50mph. However, according to BP's experts, you really start to waste money on petrol when you go over 75mph.
Given these speed limits, they're talking about motorway driving. In an article for the BBC, the AA said "Our research suggests people are cutting down on motorway speeds and sticking to the slower lanes. There's a degree of danger in going too slow if lorries come up behind you. But drivers that might have done 80 are now doing 70 and that means a significant saving."
Accelerating too hard, and hitting the brakes too hard, is another way to spend more on petrol. Even if you think that in fact you're driving sensibly and slowly to conserve fuel, you could be undoing all your hard work. Roundabouts and traffic lights are two key locations to watch out for. Smooth, steady driving works best.
Earth Easy also talks about 'Jack Rabbit' starts and hard braking claiming that this "can increase fuel consumption by as much as 40%." The site further advises that drivers "accelerate slowly and smoothly, then get into high gear as quickly as possible. In city driving, nearly 50% of the energy needed to power your car goes to acceleration."
In speed humped roads, of which there are an increasing number in the UK, you should keep to an even 15mph/20mph. Again, avoid speeding up and braking.
Don't switch into neutral to save a bit when slowing down. Cruise while in gear to slow the car down on its own. It is safer - being in neutral makes it rather difficult to pull yourself out of a tricky situation should one suddenly arise. And it uses no fuel at all.
Do you listen to the engine to know when to change gear? Start looking at the rev counter and re-tune your ear. You should change up on a petrol car at 2,500 revs. Too soon, or letting it rev too high, and you use more fuel.
I was rather surprised to find that the thing about air conditioning making a difference isn't a myth. However, it didn't quite work the way I thought.
Air con can both save you on fuel, and cost you. Although it depends on the age of your car. At low speeds, having the air con on will consume more energy. Open a window instead. However, an open window at higher speeds will increase air resistance and increase petrol consumption.
The air con on newer cars though is much more effecient, and EarthEasy advises that any difference made by turning the air con on or off is minimal.
Finally, use these online tools to help you cut down on your petrol bill. Find the cheapest petrol prices in your area using PetrolPrices.com. BP found that using its super unleaded petrol increased efficiency by 13%, and up to 28%. Well, you might think that it would given this is the more expensive petrol. But there is a current strain of thought that argues the less wear on an engine that you get from the premium brands does pay for itself in the long term.
Alternatively, if you've got a diesel car, then you could run entirely on chip fat with a bit of help. Take a look at VegOilMotoring for more information. You'll have to put up with a rather smelly exhaust though.
There's a calculator on the Environmental Transport Association's website that will tell you exactly what you're likely to spend for a range of fuel types including petrol, diesel, LPG, electric etc.
These are the main points I was able to unearth. There's lots more. For example, the jury is out on roof racks. Although many people believe these drag the car down and cause it to use more fuel, tests haven't proven this and have shown little difference between an aerodymanic car and one with a roof rack.
What nuggets of wisdom to you live by to save petrol? Are there any that you've found are actually myths, or have you been vindicated by the experts?