Why your fuel light may come on faster in this week’s cold snap
· The South African
With an orange level warning for disruptive snow still in effect over parts of the Eastern Cape, and cold, wet conditions gripping much of the country this week, most of the attention has gone to icy roads and falling temperatures.
What gets less attention is what this cold snap is doing to your fuel bill.
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Cold weather can reduce fuel efficiency by 12% to 20% or more, and the effect is worse on short trips.
According to the US Department of Energy’s fuel economy research, a petrol engine can lose as much as a third of its efficiency on trips of three to four kilometres when temperatures drop, compared to a mild day.
Why cold weather burns more petrol
A cold engine has to work harder before it reaches its most efficient operating temperature, and that warm-up period uses more fuel than normal driving.
Engine oil and other fluids also thicken in the cold, adding friction the engine has to overcome.
Denser cold air increases resistance against the vehicle, and tyre pressure naturally drops as temperatures fall, which increases rolling resistance and forces the engine to work harder to maintain speed.
Short trips take the biggest hit, since the car spends most of the journey at a less efficient temperature before the engine ever properly warms up.
Idling to warm up the car before driving does not help either, since a vehicle uses fuel while getting zero kilometres per litre while sitting still.
What this looks like in rand terms
At the current inland price of R25.58 per litre for 95 unleaded petrol, filling a 45-litre tank costs around R1 151.
If cold weather cuts your efficiency by 15%, a fairly typical figure for winter short trips, you would need roughly 6.75 litres more fuel to cover the same distance you’d normally get from that tank, an extra R173.
Diesel users feel it too.
At R26.17 a litre (wholesale), that same 45-litre tank works out to about R1 178.
A 15% efficiency drop adds close to R177 in extra fuel to travel the same distance.
For bakkie owners and anyone doing daily long-distance commutes, that adds up fast over a cold month.
What you can do about it this week
A few small habits can soften the impact while this cold front sits over the country.
Combining short errands into one trip means the engine only has to warm up once instead of several times.
Checking tyre pressure regularly matters more in cold weather, since pressure drops as the temperature does.
Avoiding long idling periods to warm up the car, and rather driving off gently instead, also helps the engine reach an efficient temperature faster.
None of this will stop winter driving from costing more at the pump, but it does explain why my own tank has been emptying faster this week than it did back in summer.
Have you noticed your fuel consumption creeping up during this cold snap?
Let us know in the comments below, Mzansi…