Karen Collier, 19 September 2015

MOTORISTS who drive out of their way for slightly cheaper fuel are pumping dollars down the drain.

Diverting more than 1.8km to snare a 1c-a-litre saving on an average tank fill is pointless once you’ve made a return trip, calculations reveal.

The benefit of a 2c-a-litre saving is cancelled out by travelling more than 3.7km out of your way and back, the RACV says. The figures assume that the same distance is covered on return.

On the flip side, driving 1km off course to save 5c a litre saves $2.24.

As Victorians prepare to hit the roads for the school holidays, the peak motoring body has measured tipping points for saving and wasting money for an average fill and fuel price.

“A ‘2-for-1’ rule is a quick way to work out whether a detour is worth it,” RACV fuel spokesman Michael Case said.

“That roughly means not going more than 2km out of your way — when making a 4km round trip — for every 1c a litre saving.”

The calculations are based on a 126c-a-litre price, a 50-litre fill, and fuel consumption of 10.9 litres per 100km.

Drivers keeping an eye out for cheap petrol can significantly cash in when big gaps exist between highest and lowest prices at different service stations.

A 20c-a-litre saving has a total return trip break-even distance of 86.6km.

Travelling 2.5km out of your way to a bargain and back still saves $9.42.

Going on a 5km hunt for the big discount and returning leaves you $8.84 ahead.

Melbourne’s increasingly unpredictable fuel price cycle keeps drivers guessing about the best time to fill up.

Metropolitan prices fluctuate between peaks and troughs. The time taken to fall from a high to low point before peaking again can stretch over two to four weeks.

Country prices are not as volatile.

Mr Case said best fuel economy was gained by accelerating gently and avoiding excessive speeds, harsh braking and long idling.

“Keep cars well maintained, properly inflate tyres, remove roof racks and other attachments when they are not being used, and remove unnecessary items from the boot,” he advised.

Extracted in full from the Herald Sun.