How to reduce those petrol costs when driving

First things first drive more smoothly. Constant gear changing and accelerating and braking use more fuel. Planning your route before you drive can save you money because you can select a route to your destination with less traffic and junctions, hence you can maintain a steady speed.
Driving a little slower will save petrol. A car travelling at 70mph uses 38% more fuel than a car travelling at 50mph.
Believe it or not but driving with the windows down will increase the amount of fuel consumed. This is because of the drag created as a result.
A cold engine uses twice as much fuel as a warm engine, and catalytic converters take 5 miles to become warm and therefore fully effective. So either avoid short journeys where possible, or drive slowly and as efficiently as possible (using the lightest pressure on the accelerator) until the engine has warmed up. In winter, don't leave your car to warm up on the drive. Use de-icer or a scraper and get going as quickly as you can. (DO NOT however, drive off until you have fully cleared your windscreen and side windows!) Moving engines warm up faster than stationary ones. and you'll be using the fuel to actually get somewhere! Also, back your car into your drive, so you can drive immediately away forwards without having to manoeuvre your car in reverse when its engine is cold. It'll save you money.

If you have a Sat-Nav use it. Program it to take you on the shortest route.
Make sure the tyre pressures on your car are correct. It has been proved that having the wrong pressure can seriously effect your fuel economy.
As time goes on it would appear that petrol prices are going to continue to increase but you can use websites to shop around to find the cheapest petrol stations in your area. Such a site is petrolprices.com
Happy Motoring.