Save 25p on a litre of petrol

Don't drive! - come on, do you really need to? Consider the health gains of walking to the shops/uni instead, or even better if it's a longer distance then cycle, and burn 600 calories an hour in the process. Take a rucksack with you for groceries or fit a basket to your bike. Also share lifts with your house mates to uni or the supermarket. Further multitask jobs rather than taking multiple short trips.
Pump up your tires - under-inflated tyres increase resistance and so use more fuel. If your tyres are under inflated by 20% this will result in a 3% fuel consumption increase and also reduce the tyre life by 30%. Go to your local petrol station and use their pump – it is normally free. Check in your car manual, inside your door or sometimes even at the air pump for the correct PSI for your car.
Stick to the limit - avoiding high speeds on motorways can save a lot of petrol. Around 50% of the power produced by the engine is used to overcome aerodynamic drag, drag increases rapidly above 70mph so you fuel consumption will suffer. The average driver travelling at 90mph on a motorway will spend £1.20 more on fuel every eight minutes than a driver travelling at 70mph, ouch! The 90mph driver will have travelled farther in that time but will still be spending 40 per cent more per mile than the 70mph driver. A recent study by What Car? magazine shows that not even 50-60mph is the most efficient speed and in fact the slower you go with the vehicle running smoothly, the less fuel you will use. The average car consumes 38 per cent more fuel at 70mph than it does over the same distance at 50mph. At 60mph it uses 34 per cent more than at 40mph.
Change gear at 2,500 revs unless more power is required. Engines run most economically at between 1,500 and 2,500 revs.
Drive smoothly - rapid acceleration and then braking excessively uses the most fuel. Avoid heavy acceleration from the lights and heavy braking can be reduced by not tailgaiting and reading the pattern of traffic ahead of you - slowing down gradually when coming up to a red light or traffic jam. Leave the heavy revving to the rude boy burning cash in his XR3i. If he'd only read this article he'd be able to afford a good car by now. By driving more smoothly, changing gear efficiently and not speeding you could save up to 60% on your fuel bill. Changing bad driving habits are the key points that really make the difference.
Close your window/cut down on air conditioning - if you are driving fast then don't have your windows open unless necessary as it causes significant drag, increasing fuel consumption. If you're cruising around town then don't worry about it as it won't make any noticeable difference, and besides you need to work on the tan on that arm! If it's hot and you're on the motorway then air conditioning is more efficient than having a window open. Yet A/C is heavy on the fuel, adding up to 8% to your bills. Anyway this is Britain not Miami Beach and you're supposed to be a student so hang on why do you even have air conditioning?!
Lose weight - in the car that is. Have a look in the boot and make sure you're not carrying unnecessary junk around, weight is the enemy of fuel economy and a car's performance - hence why F1 cars are made of posh plastic. Also try and avoid filling up with fuel until you need it otherwise you will be carrying around a lot of unnecessary weight. A tank of fuel weighs about 50kg, which will increase consumption by 2%. Not a lot but add all these up and you'll soon pass your 25% target. Also streamline - roof and bike racks add drag, increasing fuel consumption by another 2%.
Change your oil and air filter - clean oil reduces the wear caused by friction of moving engine parts, helping to improve fuel consumption. You should change the oil in a petrol car once a year or every 7500 miles. For a diesel engine it is recommended you change the oil every 6 months or 3000 miles. Clearly you need to offset the cost of the oil and doing the oil change, if you can't do it yourself. Same goes for the air filter, this is easy to change or at least check that it's still in decent nick.
Shop around - keep an eye on the prices of petrol in your area so when it comes to fill up you know which station to stop at. Or use PetrolPrices.com to find the cheapest station near your postcode. This could easily save you 5% per tank of fuel.
Other tips - other ways to save money include paying using a cashback credit card and taking advantage of supermarket petrol discount vouchers.

Is all this worth it?? - well apart from cutting your carbon footprint and doing your bit to help relieve our reliance on oil and the surging price of it then there's the money, the equivalent of £8 per tank of fuel wasted if you decide to not follow a few simples steps!!