There are many ways to save money on fuel. If you have a gas-guzzler, by far the best way to save money is to get rid of it and buy a smaller, more fuel-efficient vehicle (preferably a hybrid), while you still can. (As times get tougher, it will become more and more difficult to find willing buyers for any big gas-guzzling vehicle.) If you are buying another car, consider a manual transmission, since they use less fuel, and buy a second-hand one to maximise your savings.
Alternatively, if LPG or natural gas is available where you live, convert your vehicle to a real gas car! Fuel efficiency is slightly less, but the price is significantly lower, so you will still save plenty of money. Other alternatives worth investigating include bio-diesel, electric, and hydrogen. You could also move house to live closer to work, shops and schools.
You will also save a lot of money if you use alternatives such as public transport, walking, cycling, motorcycling, or car pooling. Fuel vouchers or dockets can save you money provided you do not have to drive out of your way to redeem them and provided the outlet has lower prices. In many areas the price of fuel changes during the week. Where I live, for example, I can save a lot of money by buying fuel on a Tuesday, which is the cheapest day for petrol here.
There are many other ways to save money on fuel in any vehicle, including driving more slowly, keeping your vehicle serviced, and reducing idling time.
DRIVE MORE SLOWLY
Recent tests done by the What Car?' magazine in the UK found that the most efficient speeds for all cars tested were below 40 mph (about 70kph). They also found the average car used up to 38% more fuel at 70mph than at 50mph. So, to save money on fuel, ease off the accelerator.
Driving slowly has other benefits besides saving on fuel because it also saves wear and tear on the brakes, not to mention your nerves, and you are less likely to have an accident, and if you have one, are less likely to be killed. You will never get another speeding ticket either.
KEEP YOUR VEHICLE SERVICED
A well-maintained vehicle uses up to 10-15% less fuel. Make sure the air filter is replaced regularly, because a dirty or blocked air filter reduces fuel efficiency significantly.
CHANGE THE WAY YOU FILL UP
Gasoline evaporates, so keep the amount of air in your tank to the minimum by filling up when the tank is half-full. This will reduce evaporation. Fill up in the morning, when the fuel is coolest (and therefore more dense). When the tank is full, do not try to put any more in because it just stays in the hose, and you will be donating it to the next customer.
KEEP THE AIR PRESSURE CORRECT
Keep the air pressure in your tyres (tires for US readers), at the maximum recommended level to reduce fuel consumption. Tyres that are under-inflated by 6psi use around 3% more fuel, so pump them up to the correct pressure, and save money on fuel. The tyres will also last longer.
REDUCE IDLING
Modern cars do not need to be warmed up as they did in the past, and any idling time is simply wasting fuel. If you are going to be stopped for more than a minute or two, turn off the engine (some modern cars do this automatically). If you have a choice of route, take the one that will mean less idling (so fewer traffic lights and bottlenecks, and less traffic). Even if the distance is slightly greater, you will use less fuel and save money.
REDUCE AIR-CONDITIONING
If you do not really need the air-conditioner on, turn it off to save fuel. You do need to run it occasionally to keep it in good condition, however, and opening windows when you are travelling at high speed will cause drag and could wipe out any savings.
SELECT THE CORRECT GEAR
If you have a manual car, make sure you select the correct gear for the speed, as the correct gear is the most fuel-efficient. The What Car?' magazine has found that a car cruising at 40mph uses 20% more fuel in fourth gear than it does in sixth. So make sure you change gear at the right time, drive smoothly, and try to anticipate gear changes and avoid sudden braking or acceleration.
REDUCE DRAG AND WEIGHT
Anything that causes drag, such as a roof-rack, will increase fuel consumption. So, if you're not using your roof-rack, take it off the car. Keep the weight down by taking things like golf-clubs out except when you are actually going to use them. In an automatic car, keep your foot off the brake pedal unless you are braking.
There are many ways to save money on fuel, as noted above. Check your fuel consumption before and after you make changes, to see how effective they are. (To check, fill the tank to the brim, note the mileage, then drive and re-fill to the brim. You can then work out the consumption in whatever units you wish miles per gallon, km per litre, or litres per 100 km.) The good thing is that saving money on fuel also saves the environment by reducing greenhouse gas emissions.