Tiwaz wrote:How would you manage your refuel trip so that you do not waste the difference in price in simple act of driving there and back?
that is important to remember... not many people take into account that going out of their way to buy slightly cheaper fuel can cost them more money ... it is also environmentally unfriendly ... but to consider it first on a cost basis
to spend less money, savings from cheaper price per litre must outweigh the cost of the detour for cheap fuel ... remembering that cheap filling stations are often on the other side of town and may be a 10 to 20 km round trip.
essentially ... giving answers in cents...
n.s > d.e.l
where
n = number of litres purchased
s = saving per litre over another filling station in
cents
d = extra distance in km driven to go and fill up
e = fuel efficiency (l/100km)
l = cost of 1 litre in
€uros
e.g. I buy 40 litres at €1.13 ... instead of €1.17 .... saves 160 cents = €1.60...
but I drive 7km there and 7 km back in a car that does 8l/100km to buy that fuel at €1.13/l... means I spend 14x8x1.13 = 127 cents = €1.27
in that case the saving is a paltry €0.33.
The take-home message is that to make a significant saving...
1) the saving per litre should be closer to 10cents/litre than 1 cent/litre
2) your car should be practically empty before you fill up
3) most importantly, you should not go out of your way to buy the fuel... take the cheaper offer only if it is on your usual routes.