Why Your Car Uses Too Much Fuel (And How to Fix It) Fuel Saving Guide
A practical guide for South African drivers tired of watching their money disappear at the pump.
Let's be honest — filling up your car in South Africa right now hurts. Petrol prices have been climbing for years, and every time you pull into a Engen or BP forecourt, you feel it in your wallet. So when your car starts drinking fuel faster than it should, it's not just annoying. It's expensive.
The good news? Most of the time, the reason why your car uses too much fuel has nothing to do with a major mechanical problem. It usually comes down to a few simple habits and easy-to-fix issues. This guide breaks it all down in plain language — no mechanic-speak, just real talk that will help you spend less at the pump starting this week.
The Most Common Reasons Your Car Uses Too Much Fuel
1. Your Driving Style Is Working Against You
This is the big one. How you drive has a massive impact on how much fuel you burn. If you're someone who accelerates hard from robots, brakes late at high speeds, or sits in the fast lane doing 140 km/h on the N1, your engine is working overtime — and paying for it.
Think of your accelerator pedal like a tap. The harder you push it, the more fuel flows through. Smooth, steady driving keeps that tap barely open. Aggressive driving throws it wide open every few seconds.
2. Your Tyres Are Under-Inflated
This one surprises most drivers. When your tyre pressure is low, the tyres flatten out slightly and create more rolling resistance — meaning the engine has to work harder to move the car forward. A tyre that's 20% under-inflated can increase your fuel consumption by up to 5%. Across a full tank, that adds up quickly.
3. You're Carrying Too Much Weight
Every extra kilogram in your car makes the engine work a little harder. People often carry tools, sports equipment, bags of sand, or even heavy subwoofers in their boots year-round. If it doesn't need to be there, take it out. A lighter car uses less fuel — it's as simple as that.
4. Your Air Filter Is Clogged
Your engine needs a clean mix of air and fuel to run efficiently. If the air filter is dirty, restricted airflow throws that balance off and the engine compensates by using more fuel. It's one of the cheapest fixes on this list — a new air filter often costs less than R200 and takes minutes to fit.
5. Your Car Hasn't Been Serviced
Old spark plugs, dirty engine oil, and a neglected fuel injector are all quiet fuel-wasters. A well-serviced engine burns fuel cleanly and efficiently. A neglected one wastes fuel every single time you start it. Skipping a service to save money often costs you far more in extra petrol over the following months.
6. You're Using the Wrong Fuel Quality
South Africa has had its share of fuel quality concerns over the years. If your car requires 95 octane and you're regularly filling it with 93, or if you're buying from a station with a reputation for issues, your engine may not be running at its best. Stick to reputable stations and use the grade your car's manual recommends.
7. Short Trips Are Surprisingly Expensive
Every time you start a cold engine, it runs rich — meaning it uses extra fuel — for the first few kilometres while it warms up. If you're making five separate 2 km trips a day, you're paying that "warm-up tax" five times. Combining errands into one trip saves more fuel than most people realise.
"Most high fuel consumption problems aren't mechanical. They're habitual — and habits can be changed today, for free."
How to Fix Each Problem (Practical Steps)
01
Drive Smoothly
Accelerate gently, look ahead to coast to stops, and maintain a steady speed on highways. Try to stay between 90–110 km/h on long trips — the sweet spot for most petrol engines.
02
Check Tyre Pressure Weekly
Most petrol stations have free or low-cost air pumps. Check your door jamb sticker for the correct pressure. Takes 5 minutes and can save you hundreds of rands a month.
03
Clear Out the Boot
Do a "boot audit" this weekend. If you don't need it daily, take it out. Losing 30 kg of unnecessary weight can make a noticeable difference on fuel bills.
04
Replace the Air Filter
Ask your mechanic to check it at every service. In dusty Gauteng conditions, filters block up faster than the manufacturer's schedule assumes.
05
Don't Skip Services
Stick to your service intervals. If you're overdue, book one this month. The cost of a service is almost always less than what you'll waste in fuel running on dirty oil and worn parts.
06
Plan Your Trips
Group your errands. Instead of separate daily trips to school, shops, and the pharmacy, combine them into one efficient loop. Your fuel gauge will thank you.
Real-Life Scenarios South African Drivers Know Well
Scenario 1 — City vs Highway
Sandton to Midrand on the N1 vs stop-start traffic on William Nicol. The same car on the same day can use 30–40% more fuel in heavy Johannesburg traffic than on an open highway. This isn't your car being faulty — it's physics. If you can shift your commute times to avoid peak traffic, even by 30 minutes, you'll use meaningfully less fuel every week.
Scenario 2 — The Loaded Weekend Car
Heading to a braai in Pretoria with 4 passengers, a coolbox, camping chairs, and a spare braai grid in the boot. That's potentially 300 kg of extra load on a car designed to carry much less. Fuel consumption can spike noticeably. For longer trips, consider what you truly need to bring — or share the load across two vehicles.
Scenario 3 — The Overdue Service
A car that was due for a service 8 000 km ago. The spark plugs are firing weakly, the oil is thick and dirty, and the air filter hasn't seen daylight in two years. This car is spending maybe 15% more on fuel than it needs to — potentially an extra R400–R600 a month at current prices. One service fixes all of it.
When to Stop DIYing and See a Mechanic
⚠ Watch for These Warning Signs
Sometimes high fuel consumption is a symptom of something more serious. If you notice your fuel gauge dropping unusually fast even after fixing the basics, or if you smell petrol inside or around your car, see your dashboard warning light come on, notice black smoke from the exhaust, or find your engine misfiring or running roughly — these are signs that need a qualified mechanic, not a YouTube fix. A faulty fuel injector, oxygen sensor, or fuel pressure regulator won't improve with good habits alone.
Bonus Tips to Improve Fuel Economy Right Now
- Turn off your air conditioner when it's not essential — it can increase fuel consumption by 5–10% in city driving. Use it on the highway where the efficiency loss is smaller.
- Don't idle unnecessarily. Modern engines don't need a warm-up idle. If you're waiting for more than 60 seconds, switch the engine off.
- Remove roof racks and roof boxes when you're not using them. Wind drag at highway speeds significantly increases fuel consumption.
- Keep your windows up on the highway. Open windows at speed create drag that works against fuel efficiency.
- Use cruise control on long, flat stretches of highway — it maintains a more consistent speed than your right foot can.
- Fill up in the morning when it's cooler. Fuel is denser at lower temperatures, so you get slightly more energy for your money.
The Bottom Line
Understanding why my car uses too much fuel is the first step to fixing it — and as you can see, most of the answers are surprisingly simple. Better driving habits, properly inflated tyres, a clean air filter, and staying on top of your services will cover the majority of cases.
The key to reducing fuel consumption isn't about spending a lot of money. It's about small, consistent habits that compound over time. Start with two or three changes this week and you'll notice the difference by the time you fill up again.
And if your current car feels like it's constantly fighting you on fuel costs — maybe it's time to consider something more efficient. Newer engines, especially those in modern small to medium-sized vehicles, are dramatically more fuel-efficient than cars from 10–15 years ago.
Ready for a More Fuel-Efficient Ride?
Browse our range of quality, fuel-efficient vehicles at Carstand in Johannesburg. Whether you're looking for a practical daily driver or a low-consumption commuter, we'll help you find the right fit for your budget.
