Highs and lows of petrol prices finally revealed in survey Battle of the bowser. ADELAIDE'S best and worse suburbs for petrol prices have been revealed through a survey held over the past six months. The results come as Adelaide ULP prices continue a long-term climb from an average of 109c/l in January, 2009, to an average 159c/l on Wednesday. Elizabeth was the most expensive suburb, with prices averaging 148.9c/l between July and December last year, according to price-comparison survey by website comparethemarket.com.au. Several suburbs, including West Torrens and Port Adelaide, shared the lowest prices during the six-month period. West Torrens recorded 148.6c/l in July and August while prices in the Port averaged 144.1c/l in October and November. Burnside recorded both the equal highest price in October - 148.5c/l - and outright lowest in December at 150c/l, the survey shows. Comparthemarket.com.au spokesman Grant Waldeck said motorists could save by shopping around. "Petrol makes up a large part of household budgets," he said. Price-conscious motorists need to seek out the cheapest service stations. They need to determine both the when and where to buy to get the best deal. Mr Waldeck said many motorists still believed Tuesday was the cheapest day of the week for petrol, but that "this is no longer the case." The one-week price cycle has now turned into longer cycles, varying from 10-22 days, in most cities. Mr Waldeck provided six tips for saving money at the bowser. THE key to filling up on a cheaper day is to keep an eye on petrol prices in your area and identify the trend. FILLING up several days before a public holiday should save a few cents per litre. TRY to avoid filling up when your car is less than a quarter full. A tank at least a third full will give you a few days to "shop around" for a reasonable price. AIR-CONDITIONING, low tyre pressures and excess weight all increase fuel consumption. BE aware of your driving habits - keeping the engine running when you're parked for longer periods, and accelerating and braking suddenly (such as over speed humps), will consume more fuel. CHECK web pages that regularly update fuel prices in your area.