Time saved
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A two-minute reality check
Going faster feels like getting there sooner. The maths says otherwise: every extra km/h buys you less time, and costs you more fuel, more money and more risk.
Over 100 km, going from 110 to 140 km/h saves just 11 min 42 s.
The 100 km lesson
Driving 100 km at 110 km/h takes 54 min 33 s. Push to 120 and you save 4 min 33 s. At 130 you save just 3 min 51 s more, and at 140 only 3 min 18 s. Each extra 10 km/h buys you less than the last.
Going from 110 to 140 km/h, 27% faster, saves just 11 min 42 s over 100 km.
Time = distance ÷ speed. That curve flattens: the faster you already go, the less each extra km/h gives back.
Drag along the curve. Watch how little the line drops once you are past normal road speeds.
Your trip
Enter a trip you actually drive. Pick your car, or type in your own fuel use, and compare driving at the limit with driving a bit faster.
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For your distance. The gap between the two dots is all the time you save.
Same trip, same car. Air resistance grows with the square of speed, so the bill keeps climbing.
What each extra 10 km/h above the limit gives you on this trip, compared with the step before.
Overtaken, and overtaken again
You overtake a truck, or someone holding the limit, and feel much faster. Later you stop for a short break. It rolls past you. A while after, you overtake it again. And at the destination, the steady driver is barely behind you.
Flat line = your break. Where the lines cross, someone overtakes.
Speedometer vs reality
The calculator assumes you hold your speed all the way. Real trips include towns, junctions, traffic and roadworks where everyone slows down. Those stretches cap your average, so cruising faster buys even less.
Dashed: an empty road with no slow stretches. Solid: real life. The faster you cruise, the less your average moves.
Your real average when you stick to the limit.
The part no fuel gauge shows
A child steps onto the road. Both drivers see it at the same moment, react in 1.5 seconds and brake as hard as they can. Here is where each car ends up.
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And in real life?
Traffic, junctions, roadworks, towns and slower cars ahead. The figures above assume you hold your speed the whole way. Nobody does.
Most of the time, the car you overtook pulls up behind you at the next red light or traffic jam.
A single speeding ticket often costs more than the extra fuel. It also gives back none of the minutes.
Speeding means more stress, more concentration and harder braking. Your tyres and brakes wear faster too.
Quick answers
Very little. Over 100 km, going from 110 to 120 km/h saves 4 min 33 s, from 120 to 130 km/h 3 min 51 s, and from 130 to 140 km/h only 3 min 18 s. Driving 27% faster, from 110 to 140 km/h, saves 11 min 42 s in total, and less on real roads with traffic and junctions.
Yes. Air resistance grows with the square of speed, so a typical petrol car uses about 20% more fuel at 140 km/h than at 120 km/h.
On a dry road, with 1.5 s to react and hard braking, a car needs about 129 m to stop from 120 km/h and about 166 m from 140 km/h. Where the slower car has already stopped, the faster one is still doing about 82 km/h.
According to the Power Model (Nilsson 2004, Elvik 2009), fatal crashes change with roughly the fourth power of speed: driving at 140 km/h instead of 120 km/h raises the risk by about 85%.
National averages updated every week: the European Commission's Weekly Oil Bulletin for EU countries and official national sources elsewhere, such as the US Energy Information Administration and Statistics Canada.