There's not much we can do about what they charge, but Today Tonight's research into fuel efficiency has discovered which petrol actually offers the best value.

Australian drivers are confronted with choice at service stations. With multiple brand names, from Vortex to V-power, and different octane ratings, it's easy to see why motorists are confused.

To help work out the mystery, five different fuels have been put to the test, using five identical Hyundai i30s on a closed circuit track in western Sydney - a real-world driving test under tightly controlled conditions, according to driving expert Ian Luff.

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"We've got perfectly smooth bitumen, dry conditions and five professional drivers ... the only difference is the fuel," Luff said.

The i30s received carefully measured doses of exactly three litres of E10, 91-octane unleaded, 95-octane premium, 98-octane super premium and diesel.

Official Government tests claim diesel delivers the best fuel efficiency, beating petrol by 30 per cent. Unfortunately for consumers, diesel is often the most expensive fuel available, and car makers charge around $3000 extra for diesel-powered cars.

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Petrol contains a tremendous amount of energy. Three litres costs less than $5 and packs enough punch to propel a 1.5 tonne car more than 40 kilometres.

Just before the 44 kilometre mark the fuel test saw its first casualty - the 95-premium car abruptly ran dry, and less than two kilometres later, so did the 91-octane regular unleaded car.

The E10-powered i30 ran dry at just over 50 kilometres, but the 98-octane ran almost five more kilometres before it too ran dry. All up, it drove nearly ten per cent further than the E10.

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Victory ultimately fell to the diesel car, after an impressive 59-kilometre endurance run.

Based on these results, a 50-litre tank of 95-octane petrol would take you 728 kilometres. Regular 91-unleaded would travel 757 kilometres, while E10 will run for 843 kilometres. But 98-octane super premium unleaded overtakes them all, crossing the line after 923 kilometres on a single tank.

The most expensive petrol beats the cheaper blends, but not the diesel - which would run for 983 kilometres.

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Luff warns drivers not to be "driven by 'the cheapest is the best' because people have to remember - you only get what you pay for."

At today's prices, over a year's worth of average Australian driving, using 95-octane will cost you $1291. Regular unleaded drops the price you pay slightly to $1140. 98-octane super premium is the most expensive, but because it drives you further the annual cost drops to $1053. Diesel crosses the line at $1002, but E10 is the most economical choice - the only fuel to push the cost below $1000 for a full year's average driving.

Even though it costs as much as twenty cents a litre more than the E10, 98-octane premium packs more kilometres into each tank, and that's why the tests showed it costs less than most other fuels in the long run. Fuel manufacturers also claim it's cleaner and greener.

"I think the difference was so marginal when you really look at it, for the minimal saving you're going to get with the E10, my money's on going for the premium quality fuel," Luff said.

Colin Long from the New South Wales Service Station Association agrees that E10 isn't necessarily the best choice for all motorists.

However he also says "certainly it's good to buy the cheapest product because if you're a strict budget, that's the way to go."

According to Dr Tim White from the University of New South Wales, despite the fact that E10 is the cheapest fuel on offer, it still poses potential problems for Australian motorists.

"The problem with E10 isn't so much actually burning the alcohol in the engine. It is that the alcohol is hydroscopic - that it can actually absorb water from the atmosphere when it's in an open tank, particularly in the ground tank at the petrol station," Dr White said.

"Water still can get into the fuel system and you may still have these problems of blocked filters and rough running - even in a brand new car."

This reporter is on Twitter at @cadoges