Many drivers trust the dashboard's "average fuel economy" display — and many suspect it's wrong. To know your car's true consumption, you only need two fill-ups. Let's make fuel math simple, plus a few habits that save money at the pump.
The Fuel Consumption Formula
Consumption per 100 km = Fuel used (L) ÷ Distance driven (km) × 100
Correct method: fill up and note the odometer → drive normally → fill up again (note the fuel added) → compute with the distance between the two fill-ups.
Example: 40 L added, 520 km driven → 40 ÷ 520 × 100 ≈ 7.7 L/100km.
Cost per Mile (or Kilometer)
Multiply consumption by fuel price: cost per km = consumption × price ÷ 100.
At $1.05/L (≈ ¥7.5) and 7.7 L/100km, that's about $0.08/km. Skip the manual math — enter fuel added and distance into the fuel calculator for instant L/100km and cost per km.
How Far Does a Full Tank Get You?
Tank capacity ÷ consumption per 100 km × 100 = theoretical range. A 55 L tank at 7.7 L/100km gives roughly 714 km of theoretical range — real range dips with road conditions, AC, and load.
Common Causes of High Fuel Use
- Low tire pressure: more rolling resistance, 5%–10% worse consumption
- Frequent hard acceleration / braking: stop-and-go city driving is the thirstiest
- Long idling / over-warming: burning fuel without moving
- Dirty oil or air filter: lower engine efficiency
- Air conditioning: on the highway keep windows up; in the city AC can be more efficient
Five Fuel-Saving Driving Habits
- Drive smoothly: hold a steady speed, avoid hard acceleration and braking
- Windows up on the highway: drag rises with windows down; AC can be cheaper at speed
- Stay on top of maintenance: regular oil and filter changes
- Check tire pressure: proper pressure saves fuel and is safer
- Plan your route: avoid congestion and detours
When to Watch Fuel Use Closely
If consumption jumps noticeably on the same route, it may signal a problem (aging spark plugs, a faulty oxygen sensor, etc.). Get it checked early — catching it soon saves fuel and money.
Open the fuel calculator now, enter your two-fill-up data to find your car's true consumption, and pair it with these tips to make every drop count.